Sacrificing three other artifacts can be a lot, but the Forgemaster can sacrifice itself to make it easier
Good sacrifice targets usually fit one of these categories: Enters value: creatures like Solemn Simulacrum or Elvish Visionary that already replaced part of their cost Dies value: creatures with death triggers, recursion, or graveyard payoffs Mana value 3 or 4 creatures: these create the best early Emerge curve Artifact fodder for Emerge from artifact: eggs, Wellsprings, Clues, Blood tokens, and similar pieces Recursive creatures: threats that come back from graveyard or exile Creatures you wanted in the graveyard anyway: because some decks treat the graveyard like a second hand with worse lighting The practical sweet spot is often mana value 3 or 4
Its lead by the infamous Derevi, Empyrial Tactician, using its ability to untap permanents to play around lockdown pieces like Stasis and Winter Orb while opponents struggle to get enough mana to do anything
Thundermaw Hellkite 7.5 Such a heavy and quick threat for the mana
When it enters the battlefield or dies, you get to exile a permanent
That is to be determined, but you can bet that players will be throwing this in all styles of Commander decks to try out the new card