Trollhide

An Aura that does two jobs at once: the +2/+2 is the body-buff every green pump enchantment offers, but the granted regeneration is what justifies committing a whole card to a single creature. A host carrying Trollhide stops trading down in combat. It blocks a larger attacker and survives, it walks into a sweeper that destroys (rather than exiles or sacrifices) and comes back, and it shrugs off most targeted removal so long as the controller keeps a green and a colorless mana open. The catch is the standard Aura tax: it folds the moment the host is bounced, exiled, or forced to be sacrificed, and it leaves you down two cards if the creature dies before the buff matters. Regeneration as a granted keyword has always been defensive technology, a way to make a board commitment sticky without protecting it from everything, and stapling it to a stat boost on one permanent concentrates that risk onto a single target. The reward, when it holds, is a recurring blocker or attacker the opponent has to answer with the right kind of removal rather than just any removal. That conditional durability, not the raw +2/+2, is what the card is selling.