msem-instigator

Your life total becomes 0. Until an opponent's next turn, you can't lose the game, your opponents can't win the game, and you can't gain life.
Take an extra turn after this one.
Exile Buy Time.

This spell costs {X} less to cast, where X is 20 minus your life total.
First strike, menace, trample

Whenever you cast a noncreature spell, upgrade Embodied Soul. (Give it one of the listed counters it doesn't already have.)
• Flying
• First strike
• Vigilance
• Lifelink
{W}: Until end of turn, if Embodied Soul isn't a creature, it becomes a 0/0 Spirit Avatar enchantment creature with “This creature gets +1/+1 for each different kind of counter on it.”

Flying, lifelink
When Facsimile of Divinity enters, it deals 4 damage to any target.

When Lilyreed Triton enters, create a white Aura enchantment token named Triton's Gift attached to target creature. The token has enchant creature and “Enchanted creature gets +1/+0 and can't be blocked by creatures with power 3 or greater.”

Counter target spell unless its controller pays {1} for each card in their graveyard.

Hexproof
Augmented — At the beginning of each end step, if you've spent {W}{U}{B}{R}{G} to cast spells this turn, untap up to three permanents. Then you may shuffle your hand into your library. If you do, draw three cards.

Prevent all combat damage that would be dealt this turn.
Draw a card.

Flying
Whenever you cast a spell from exile, each opponent loses 2 life.

Winnow (Damage dealt to this creature also causes you to lose that much life.)
Whenever Vicious Slasher attacks, target creature gains winnow until end of turn.