When does a character start to fall? Can a character use a power or ability mid-air before falling?
Example:
An Eladrin Fey Pact Warlock is standing on the edge of a chasm and kills a cursed enemy. Misty Step allows the Warlock to teleport 3 squares, and he does so, directly over the chasm (mid air). The Eladrin then activates Fey Step to teleport the remaining spaces to the other side of the chasm.