The Tarrasque

Straight out of Dungeons & Dragons, this is the monster the source material built to be functionally unkillable, and both of its signature clauses hang on the same condition: it has haste and ward 10 only if it was cast. Pay the full nine mana, whether off ramp or off a full board's worth of lands, and it lands swinging while shrugging off nearly any targeted removal or aura. Cheat it in through reanimation, a blink effect, or a token copy, though, and both protections evaporate at once, leaving a defenseless 10/10 that cannot even attack the turn it arrives. That gating punishes the shortcut and rewards the front door, a pointed reversal of the usual instinct to bypass a nine-mana bill entirely. The attack trigger is where the fiction snaps into mechanics, forcing a fight with a defending creature before combat damage, and with a 10/10 doing the fighting that clash almost always kills the targeted creature outright, folding a removal spell into every swing. But note the missing keyword: without trample, the defending player can simply throw a fresh chump in the way each turn, feeding one creature to the fight and another to the swing. It is a wrecking ball, not an unstoppable finisher: an apex predator that faithfully models its legend right down to the fact that it can still be gummed up by bodies.