Hecatomb

Four creatures, the entry tax, and it is total. Either you convert a developed board into a standing damage engine in one transaction, or the whole thing crumbles on arrival. What the sacrifice buys is a pinger gated only by untapped Swamps; each tap deals one damage to any target, and the rate of fire scales with how many Swamps you control rather than any per-turn limit. The design tension is the one-time price against the open-ended payoff: spend everything once, then drain creatures, planeswalkers, and faces a point at a time while the mana keeps flowing. It is a glass cannon dressed as an enchantment, exposed in the window after the creatures are spent but before the damage has added up, devastating once the Swamps outnumber whatever the opponent can rebuild. The four-creature clause is the kind of all-or-nothing gate early design favored when it wanted a powerful effect to demand a genuine board commitment instead of a mana payment, which places Hecatomb in the lineage of sacrifice-fueled payoffs that treat your own creatures as ammunition rather than as threats.