Implosion is a legendary major card out of the New mechanic pool. Grand Convergence drags every enemy within 6 u into the rally point before the wisps strike.

You can take it once · it only turns up when your Special ability can actually use it · it can be offered for 0 of the 34 abilities.

Only one card can reshape that ability this way — this one, or Double Rally and Far Convergence. Take one and the rest are gone for the run.