Blade Cascade
Blade Cascade is a 4e Dungeons & Dragons 15th-level Ranger daily power. Before it was errata'd into sensibility, the ability allowed a two-weapon ranger to make a theoretically infinite number of alternating attacks, and was especially potent when combined with other abilities that allowed re-rolls of attacks to avoid missing. Kenshiro Cascadero "Rattata" Orcuslayer was designed around the abuse of this ability, which proved extremely powerful. In its most optimized form, a Fey Warlock with Blade Cascade could, with the help of a Battle Captain, annihilate an entire army in one round, teleporting every time she ran out of adjacent targets.
Unfortunately for Kenshiro, after a month or so, Wizards of the Coast released errata that capped the number of attacks that could be made at five, rendering the ability significantly less powerful and forcing Kenshiro to bring an Orbizard along if he wanted to beat the shit out of Orcus without fear of any retaliatory strikes.