Hallowed Ground is a legendary major card out of the New mechanic pool. Sanctuary covers 14 u for 4 pulses (10 s) at 40% of its heal and damage.

You can take it once · it only turns up when your Ultimate 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 Eternal Sanctuary and Searing Sanctuary. Take one and the rest are gone for the run.