dirty yugioh cards YU-GI-OH! - Card Destruction (LCYW-EN060) - Legendary Collection 3: Yugi's World - Unlimited Edition may be 1st or Unlimited Edition Yu-Gi-Oh: 15 Funniest Monster Cards

There are several Edict effects for enchantments in black, such as Pharikas Libation and Invoke Despair

What this means is that, should the Troll take lethal damage from something (say from combat, or your opponent casting Pyroclasm), the Troll will stay alive as long as you pump two mana into him

There were multiple combo decks, for existence, that took advantage of this rule

[Update 30 May 2025] Another variant of this deck has recently arisen

There are some extreme edge cases where you could hold up Lotus and Twister/Wheel, and then reset the board state entirely with this, but otherwise, its a lot of mana for not a lot of benefit