Emergent Ultimatum

Exile the top five cards of your library. An opponent separates those cards into two piles. You may play lands and cast spells from one of those piles. If you cast a spell this way, you cast it without paying its mana cost.

Choose five permanents you control. For each of those permanents, you may search your library for a card with the same name as that permanent. Put those cards onto the battlefield tapped, then shuffle.

Each opponent exiles cards from the top of their library until they exile a nonland card. You may cast any number of spells from among those nonland cards without paying their mana costs.

Rebound (If you cast this spell from your hand, exile it as it resolves. At the beginning of your next upkeep, you may cast this card from exile without paying its mana cost.)

Each opponent exiles cards from the top of their library until they have exiled cards with total mana value 5 or greater this way. Until end of turn, you may cast cards exiled this way without paying their mana costs.

Draw three cards. Then target opponent faces a villainous choice — They discard three cards, or you may cast a spell from your hand without paying its mana cost.

This spell costs less to cast for each 1 life your opponents have lost this turn.

Target opponent exiles the top three cards of their library. Until the end of your next turn, you may play those cards. If you cast a spell this way, mana of any type can be spent to cast it.