This means that the Background can have a different color identity from the legendary creature and you use the combined color identity of both the legendary creature card and the legendary Background card to determine what the other 98 cards in your Commander deck (or 58 cards in Commander draft) can be
Donato's rendition is found on all subsequent sets, with just a single outlier: a collector-themed release titled "From the Vault: Dragons. The From the Vault card was treated to new artwork, like most other cards from the collector-oriented sets, and illustrated by Justin Sweet
These are your real chase cards
As of right now, there are 32 cards that have this ability, each marked with a Choose a background text
It's in the conversation for best colorless removal spell of all time, which is notable, although just how much that matters is up for debate
Your opponent can respond to the ability or spell afterward, but the creature you sacrificed is already in the graveyard
