Farewell is the gold standard of white board wipes — a modular nuke that lets you exile exactly what's threatening you.
The exile clause is the key selling point. Unlike Wrath of God, Farewell ignores indestructible, sidesteps death triggers (no aristocrats payoffs, no recursion), and shuts off graveyard strategies entirely. Hitting all four modes is a full reset that leaves opponents with nothing to rebuild from. The flexibility means you rarely waste it: blow up just artifacts vs. an affinity deck, just creatures and graveyards vs. reanimator, etc.
Every white deck can run this, but it shines in control, stax, and lower-power-curve decks that want to stabilize and out-grind opponents. It's a Game Changer because exiling everything is brutally efficient and hard to interact with.
When NOT to play it: in fast aggro or go-wide token decks where you're usually ahead on board — you don't want a six-mana symmetrical sweeper that hits your own engine. Decks built to recur threats also dislike paying that much for a one-sided wipe they'd rather make asymmetrical.
If you choose more than one mode for Farewell, you perform the actions in the order written.