Undertow Crest is a legendary major card out of the New mechanic pool. Returning Wave's homing leg deals 300% while the outbound leg deals 65%; reach 30% longer.

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 Standing Tide and Tidal Bore. Take one and the rest are gone for the run.