Ability Charge

Some hero abilities use the ability charge mechanic. These abilities have charges on them that replenish over time. They can be used continuously, with each use consuming 1 charge, until there are no more charges.

Known bugs
In Ability Draft, charge-based abilities can be "recharged" by Tinker's. This causes the abilities to be usable even at 0 charges as long as there is enough mana to use them. Since Rearm is an Ultimate ability and Ember and Earth Spirit are not part of Ability Draft, this can only be (ab)used in conjuction with Sniper's and Broodmother's.