Changes from DotA

DotA, or Defense of the Ancients, is a custom map created for the Blizzard game, Warcraft 3 and Warcraft 3: The Frozen Throne. Many elements were borrowed from the game and it is based on its engine. Dota 2 is a complete game created by Valve on the Source Engine, however, and many differences exist due to copyright concerns, engine disparities as well as various bugs or intended changes to Dota 2.

Hero gameplay changes

 * 's cannot explode while in mid air. It will always hit the enemy.
 * 's now stops Fountain healing.
 * 's projectile cannot be seen with True Sight. (Enemy cannot dodge it now even if it goes though towers)
 * 's 's is triggered by killing a unit with.
 * 's will no longer award gold after it has been dispelled.
 * can keep auras during his, so , , and others all properly function. The auras are first transferred to the Earth. If the Earth is killed, it will transfer to the Storm and then the Fire if killed.
 * 's additional has an effect indicator.
 * can now walk properly in her web while in trees.
 * 's (without ) will latch to neutrals.
 * 's cannot freeze the enemy's Fountain
 * and now also work on  using  (as well as 's  and ).
 * 's can hit invisible units and those in fog.
 * can no longer cast while silenced. (Also with the cast backswing disabled in Dota 2, he can cast spells and attack much faster)
 * 's can block  and.
 * can no longer kill s with.
 * 's now applies a regular stun, as opposed to a pause effect. So bashed units coming out of Chronosphere won't have the additional stun time, and heroes with toggleable abilities such as  and  can continue using their abilities inside Chronosphere. Another effect is that cycloned units won't fly for the full duration inside the Chronosphere.
 * can no longer kill couriers with.
 * 's delay effect cannot be seen with True Sight.
 * can no longer follow across the map while charging with.
 * It is now much easier to surround heroes with 's.
 * 's now has a marker at where it will crash.
 * 's now leaves a trail.
 * 's no longer cancels 's.
 * 's no longer has strange interactions with various orbs and critical strike effects and will not break on acquiring them or procing them.
 * 's can now dodge projectile stuns even when under True Sight.
 * can morph an attribute to 0.
 * 's does not dispel any buffs/debuffs from hero that can be used to locate the real hero (e.g., , , etc.).
 * won't receive a temporary 3 second buff when you level the ability for the first time.
 * Orb walking with and  while having lifesteal works correctly now.
 * 's now has a visual indicator that shows when its duration will end (via an expanding red ring).
 * Stolen intelligence from is now displays as a buff.
 * 's is now much more visible, making her easier to spot.
 * 's leash can now be broken by a multitude of spells such as, , , , etc.
 * 's can be canceled.
 * 's duration and damage do not get reduced against tougher creeps (no level 6 penalty in Dota 2).
 * 's no longer lets affected units attack if they possess an orb effect like  or.
 * and can be seen while attacking when under  and under their own invisible buff.
 * 's does not interrupt.
 * Silence no longer stop 's.
 * 's now works on all abilities, whereas engine limitations prevented Rubick from stealing some abilities in DotA. (See Spell Steal Interaction for more information)
 * can no longer get souls from.
 * 's now gains souls immediately upon killing a unit instead of needing to wait for it to reach him. This also applies to 's.
 * 's can no longer be evaded with invisibility.
 * 's stun now also goes through magic immunity.
 * 's does not proc.
 * can now walk properly through 's spectral path.
 * 's is not interrupted by instant cast items like  or.
 * 's occurs AFTER the attack animation finishes, instead of before.
 * 's area of effect while Charging is smaller (possibly due to above change).
 * 's can no longer splash damage of abilities (e.g., ).
 * 's is centered on the cast point instead of himself like in DotA. You'll have to cast it on himself to reproduce the same effect as in DotA.
 * 's +  combo does less damage than in DotA and damage occurs with less instances. (Max 5 in Dota 2 vs 10 in DotA).
 * 's can cancel 's  and 's.
 * 's stacks only lasts 6 seconds on Roshan.
 * 's first attack after can proc.
 * can interrupt with.
 * 's now goes through.

Fog of War changes

 * Losing sight of the enemy in the fog no longer "stops" your unit. Instead it will keep following them to the last seen location, it will keep using basic attacks without any additional input if you regain vision of it. If the unit is ranged, any projectiles in the air will follow them through the fog, allowing you to track the location (although the models of these projectiles sometimes stop rendering after entering the fog).
 * To DotA players, this means you are often better off leaving your hero on auto-attack rather than clicking ahead. After you cast a spell, reclick to keep your hero "locked" on. This also means juking is harder to perform.

Item changes

 * additional mana can now give over your maximum mana pool, making it more useful. So now you can use soul ring then spell rather than spell, soul ring, spell when at full mana.
 * now removes as well.
 * no longer damages the owner of wards. Eg, and.
 * no longer has a projectile (no double gold trick).
 * can now also be used by 's Lone Druid Spirit Bear model.png Spirit Bear.
 * can now be used by 's Lone Druid Spirit Bear model.png Spirit Bear and is normally affected by the health drain but does not benefit from the strength bonus.
 * is now a Unique Attack Modifier.
 * 's bonus speed now stacks with other scepters.
 * (both ranged and melee versions) will now work with items that grant Lifesteal, but are both Unique Attack Modifiers.
 * can be used in conjunction with.
 * can be used in conjunction with.
 * do not prevent, , or items that grant Critical Strike from procing.
 * no longer grant invisibility through outside of tree range during phase duration.
 * now works with Unique Attack Modifiers. (Also works on 's, but only on the main target), in DotA the extra damage was disabled when you had an orb.
 * and no longer grant the mana aura to creeps while toggled off.
 * 's backstab damage and other critical strikes stack, so instead of either one procing, both are applied.
 * can be used in conjunction with.
 * Storing a rune in a is now done by picking up the rune with the Bottle in the inventory, instead of using the empty Bottle on the rune. This also allows the Bottle to store runes even when not empty.
 * A with a rune in it is no longer a shareable item (in DotA it could not be used anyway).
 * You can instantly refill a by giving allies the bottle as soon as they teleport in from the fountain (since allies retain the fountain regen aura for a few seconds).
 * now stacks with.
 * can be used with and.
 * Items can be combined even if you don't have to slots for it.
 * Lightning attack modifier ( and ) only counts as an attack modifier when it procs, so it stacks with other orb effects.
 * Courier is automatically upgraded to a flying version when a player buys the flying recipe, no longer needing the courier to pick it up.
 * Courier control is shared automatically, there's no option to take away control.
 * Flying courier can no longer be flown close enough to give vision to enemy fountain area without been killed.

Misc. changes

 * The original teams names have been changed, Sentinel has been changed to Radiant and the Scourge has been changed to Dire.
 * Individual heroes are no longer affiliated with Radiant or Dire. (Refer to these pages for lists of heroes formerly affiliated with each faction.)
 * All changes from patches 6.82 onward were not applied to Dota 1 (except for 6.83c and 6.83d).
 * Neutrals spawn 1 second later rather than exactly at the full minute mark like in DotA. (Spawn triggered at end of full minute mark rather than beginning)
 * Neutrals no longer sleep at night.
 * Each tree has its own timer as to when it'll grow back as opposed to having a global timer for all trees.
 * Bonus gold is no longer granted to assisting heroes if First Blood is taken by a tower or creep.
 * Casting backswing animation no longer occurs when auto attacking. (e.g. heroes will now ignore their backswing animation if an enemy hero is in attack range and will immediately start auto attacking or running towards them. Most noticeable on heroes with long animations are in DotA.)
 * You can pick up runes while ed.
 * Cleave works against flying units (except 's familars).
 * You can't cancel attacks while under and.
 * You are no longer blocked by items while invisible.
 * You can't cancel with,  or.
 * Spirit Bear does 60 more damage than DotA, also occasionally does 4 ticks instead of 3 for additional damage. Damage also bypasses damage block reduction.
 * Damage block procs when damage source is invulnerable (it doesn't in DotA), making less effective against,  and  (and other like items).
 * Using, or  across certain map areas have been removed, while  can go out of the map boundaries.
 * Teleports (notably that of ) will be broken if the unit being teleported to has been dominated by the enemy.
 * Projectiles are coded to take effect when it hits rather than when its cast, so you could have things like a ranged triggering bash or cleaving with  or using Lifesteal auras by switching it to melee before it hits.
 * If somebody is marked by and returns, it always cancels channeling spells, even if they didn't move. This is useful if you have to interrupt something like an  where  would be too slow.
 * Right click follow on your allies' heroes does not auto attack the target of the followed unit (where as they did in DotA).
 * Sounds from different lanes outside of screen range can be heard occasionally.
 * Creeps will not run while under effect of the Wildwing Ripper's Tornado.
 * Dark Troll Summoner can raise Skeleton Warriors from ability kills that normally don't produce corpses (eg, , , illusions).
 * The Ghost's Frost Attack is now a passive ability instead of an autocast attack modifier that costs 12 mana on each attack.
 * You can't tell when Roshan has respawned with the neutral green indicator anymore as in DotA.
 * Roshan's Spell Shield doesn't trigger on, or.
 * There's no messages to tell when the will expire.
 * You can now see the cooldown timers, mana bars and abilities of your allies.
 * Hotkeys are customizable without custom keys or 3rd party programs
 * Abilities can be leveled up while dead.
 * You now have an item stash where only you can access.
 * Disassembling can be done by right clicking an item instead of placing the item in the player's Circle of Power.
 * AI practice bots are implemented natively.
 * You can resell items within the first ten seconds for full price, if they were not combined or activated.
 * The Fountain is now invulnerable.
 * Hero can no longer be deselected (except for selecting other controllable units, such as Couriers or pets)
 * Observers and replays will show a circle indicating when Roshan will respawn.
 * Item shops are condensed (there are now only the main shop, side lane shops, and secret shops)
 * Orb Effects are called Unique Attack Modifiers.
 * Control Groups now save between summons for summoned units (even when they die)
 * Items and many heroes have entirely new lore.
 * Most abilities now stack. For example, abilities that apply the common 30% MS 20% AS slow:, , ; also with and.
 * Extending the previous point, many ability and item interactions that existed due to its hard-coded nature don't exist anymore. For example, does not remove.
 * Damage and stun types of bashes now depend on the source of the bash instead of the range of the hero (used to be magical damage / physical stun on melee and the opposite for ranged). Abilities from heroes work like in DotA, gives magical stun and damage, and  works like melee.
 * Damage from multiple s stack if they proc at the same time. It doesn't override any other on-hit effect either.
 * There is no text above 's projectile displaying which spell was stolen in Dota 2.
 * Most healing/mana regeneration sources (such as, Fountain regeneration, and the ) now restore health and/or mana in the form of HP/mana regeneration (with 10 regeneration instances per second) instead of applying a single instance every second.
 * Fountain regeneration now lingers for a full 3 seconds after leaving the fountain area.
 * Various ability renames: most Wind Walk abilities were given alternative names, and a few ability names were changed to make their effect more obvious ('s Impale became Earth Spike, for example).
 * Due to different engine and ability interactions you may find the gameplay and power of different heroes very different to DotA!

Items name changes
Due to copyright concerns, some items and heroes in Dota 2 have different names from their DotA equivalent.
 * Ancient Janggo of Endurance is now Drum of Endurance
 * Boots of Elvenskin is now Band of Elvenskin
 * Buriza-do kyanon is now Daedalus
 * Circlet of Nobility is now just Circlet
 * Cranium Basher is now Skull Basher
 * Eaglehorn is now Eaglesong
 * Guinsoo's Scythe of Vyse is now just Scythe of Vyse
 * Headdress of Rejuvenation is now just Headdress
 * Kelen's Dagger is now Blink Dagger
 * Khadgar's Pipe of Insight is now just Pipe of Insight
 * Lothar's Edge is now Shadow Blade
 * Mask of Death is now Morbid Mask
 * Messerschmidt's Reaver is now just Reaver
 * Nathrezim Buckler is now just Buckler
 * Ogre Axe is now Ogre Club
 * Planeswalker's Cloak is now just Cloak
 * Sobi Mask is now Sage's Mask
 * Stygian Desolator is now just Desolator

Hero name changes

 * Aggron Stonebreaker the Ogre Magi is now Aggron Stonebreak the Ogre Magi
 * Alleria the Windrunner is now Lyralei the Windranger
 * Anub'arak the Nerubian Assassin is now simply Nyx Assassin
 * Anub'seran the Nerubian Weaver is now Skitskurr the Weaver
 * Aurel Vlaicu the Gyrocopter is now Aurel the Gyrocopter
 * Azgalor the Pit Lord is now Vrogros the Underlord
 * Banehallow the Lycanthrope is now just Banehallow the Lycan
 * Cairne Bloodhoof the Tauren Chieftain is now Elder Titan, the Worldsmith
 * Centaur Warchief is now Centaur Warrunner
 * Clockwerk Goblin is now just Clockwerk
 * Darchrow the Enigma is now just Enigma
 * Daelin Proudmoore the Admiral is now Kunkka the Admiral
 * Doom Bringer is now just Doom
 * Dwarven Sniper is now just Sniper
 * Eredar the Shadow Demon is now just Shadow Demon
 * Furion the Prophet is now simply Nature's Prophet
 * Goblin Techies are now just Techies
 * Icarus the Phoenix is now just Phoenix
 * Jin'Zakk the Batrider is now just Batrider
 * Kael the Invoker is now just Invoker
 * Kel'thuzad the Lich is now Ethreain the Lich
 * Leoric the Skeleton King is now Ostarion the Wraith King
 * Lina Inverse the Slayer is now just Lina the Slayer
 * Luna Moonfang the Moon Rider is now just Luna the Moon Rider
 * Magnus the Magnataur is now Magnus the Magnoceros
 * Magina the Anti-Mage is now just Anti-Mage
 * Mirana Nightshade the Priestess of the Moon is now Mirana the Princess of the Moon
 * Murloc Nightcrawler is now Slark the Nightcrawler
 * Necrolyte is now Necrophos
 * Nessaj the Chaos Knight is now just Chaos Knight
 * Obsidian Destroyer is now Outworld Devourer
 * Pandaren Brewmaster is now just Brewmaster
 * Pugna the Oblivion is now just Pugna (although "oblivion" is still referenced in his lines and lore, he possesses no title in Dota 2)
 * Rexxar the Beastmaster is now Karroch the Beastmaster
 * Rikimaru the Stealth Assassin is now Riki the Stealth Assassin
 * Rizzrak the Goblin Shredder is now Rizzrack the Timbersaw
 * Rylai Crestfall the Crystal Maiden is now just Rylai the Crystal Maiden
 * Shendelzare Silkwood the Vengeful Spirit is now just Shendelzare the Vengeful Spirit
 * Syllabear the Lone Druid is now Sylla the Lone Druid
 * Terrorblade the Soul Keeper is now Terrorblade the Demon Marauder
 * Thrall the Disruptor is now Disruptor the Stormcrafter
 * Tuskarr is now simply Tusk
 * Vol'Jin the Witch Doctor is now Zharvakko the Witch Doctor
 * Zeus the Lord of Olympus is now Zeus the Lord of Heaven

Buff placers
Buff Placers refer to a group of Items in DotA that applied a buff to a hero's attacks. Typically, they were also Orb Effects. Unlike Orb Effects, which do not stack for balance reasons, the Warcraft 3 engine was limited in that it only allowed one buff to be applied per attack. This meant that Buff Placers did not stack. In Dota 2, however, Buff Placers will now stack with each other. For example, Venomancer's Poison Sting will now stack with Desolator, even though both of them were Buff Placers in DotA.