Clockwerk

Rattletrap the Clockwerk is a melee strength hero commonly played as an initiator or ganker. As an initiator, his main purpose is crowd control. However, he also does secondary jobs such as chasing and map control. His abilities are centered around isolating and killing enemies one by one. He does not deal reliable area damage like most initiators, but still he is capable of a surprising and devastating entrance. Usually Clockwerk players should initiate onto low health support heroes or enemy heroes with strong team fight ability, such as Warlock, hampering their ability to land solid teamfight spells. Clockwerk can also initiate onto enemy carry heroes, in order to isolate them away from the team fight by forcing them to remain in cogs.

Gameplay
His first ability is Battery Assault, which shoots out shrapnel every 0.7 seconds for 10.5 seconds in total. This spell deals good damage and causes mini-stun on every hit. It has a very small area of effect and is not effective when multiple targets are near Clockwerk, so it is beneficial to isolate heroes or hunt lone heroes down. If you can consistently hit one enemy hero over the 10.5 seconds, it deals an incredibly high amount of damage. His second ability is Power Cogs, which sucks in units that are close to him and surrounds them with small structures. These structures don't allow anyone to escape and will push back heroes that try to get close to them, which makes it very useful to combo with his first ability. Can also be used to run away or create an artificial wall, but this requires skill on the player's part. His third ability is a global rocket which has a decent area of effect but a slow travel time, so it is difficult to hit from long range. It gives vision wherever it hits and deals some mediocre damage, making it effective to scout, harass, or kill a fleeing hero. Clockwerk's ultimate is a very long range hookshot which shoots out very quickly from him to a target position. If the hook collides with an enemy hero or creep, he will be pulled to it(the target is immobilized while he's being pulled unto it), stunning and damaging all enemies that are passed through, as well as those at the target location. It is very good for catching heroes that are running away or off guard, but takes positioning and skill to hit.

Source:

Tips

 * Clockwerk is a formidable ganker with nice farming capabilities who can be effective even with very few items in the early and mid game. This makes you comfortable at almost any lane; side lane, mid lane or solo lane are all viable options.
 * Clockwerk has great synergy with high DPS nukers. Power Cogs can isolate a single enemy and set them up for AOE or single-target nukes.
 * Clockwerk has two very powerful escape mechanisms in Power Cogs and Hookshot. Use them to enter fights or escape.
 * Battery Assault works as a ministun, and is effective for interrupting channeled spells or teleports. This prevents heroes from casting spells with extended cast times.
 * You can spam Rocket Flare to gain map control due to the vision it provides. Consider using it before the game starts to find out where enemy heroes are.
 * You can utilize the global cast range of Rocket Flare to kill fleeing opponents.
 * If a rocket flies over an empty neutral camp exactly during their respawn timer (every 1 minute), it will be counted as blocking (similar to ward blocking) and thus no neutrals will spawn there. However, this requires extremely precise timing, as the rocket needs to be 'physically' present there, not after it explodes.
 * Clockwerk is a mortal threat to many heroes. However, his spells scale off late game. Be sure to have a strong ganking presence in the mid game to create space for your team.
 * Necronomicon is also a good item to get on Clockwerk. The damage from the summoned units, mana burn, and the true sight all synergize well with Clockwerk's ability to trap enemies in his cogs.
 * Force Staff is also a good choice to be able to quickly escape your own cogs, while leaving opponents trapped inside. This is especially useful against heroes that can rapidly deal melee damage (e.g. Slardar, Alchemist, Lifestealer,etc).

Trivia

 * One of Clockwerk's death animations is a reference to the movie Terminator 2: Judgment Day.
 * An old competitive strategy that was used in DotA was sending a rocket flare over to the enemy fountain, and having Nature's Prophet teleport to the enemy base and snipe the courier. This tactic has long been discontinued due to triggers being implemented to stop it.
 * The line " Ratt_death_05.mp3 I'm lost... like gears in the rain." (death line) is a reference to the movie Blade Runner.
 * The line " Ratt_spawn_02.mp3 Some assembly required" (spawn line) is a reference to a song of the same name composed by Mike Morasky, for the game Portal 2, another game made by Valve.
 * The line " Ratt_respawn_16.mp3 I'm the six million gold piece man!" (respawn line) is a reference to the American television series The Six Million Dollar Man.
 * The line " Ratt_move_24.mp3 The turtle wins the race" (move line) is a reference to one of Zeno's Paradoxes named Achilles and the tortoise.
 * According to some of his responses Tinker and Sniper are his cousins.