Lurrus of the Dream-Den

Among the ten permanent-guarantees offered by companion, this Cat Nightmare demanded the least and returned the most. Capping every permanent at mana value two or less barely registered as a cost, because the decks that wanted it were already stacked with cheap artifacts and one-drops; the reward was a recursion clause that turned each destroyed permanent into a resource you could buy back once per turn, converting every trade into a grinding attrition loop that refuels itself. That lopsided math is precisely what forced the mechanic's rewrite: the companion condition was errata'd so the card must be paid for and moved into hand before it can be cast, converting a free extra card into a genuine tempo commitment.

The change slowed it without saving it. This remained the companion that broke the most formats, banned in Legacy and Vintage where the sub-three-mana permanents it could reanimate (the cheapest Moxen, cost-reducers, one-drop artifacts) chained into loops the mana-value restriction was never built to permit. The lifelink and the 3/2 body are almost beside the point; the real design object is the repeatable graveyard toolbox, a permanent-value engine bolted to a creature you could reliably summon from outside the game in every game. It endures as the clearest cautionary tale of the companion experiment: reliability and recursion, handed over together at almost no deckbuilding price, proved too much for any format to contain.