Sephiroth, One-Winged Angel

Flying
Super Nova — As this creature transforms into Sephiroth, One-Winged Angel, you get an emblem with "Whenever a creature dies, target opponent loses 1 life and you gain 1 life."
Whenever Sephiroth attacks, you may sacrifice any number of other creatures. If you do, draw that many cards.

Have

Sephiroth, Fabled SOLDIER

Whenever Sephiroth enters or attacks, you may sacrifice another creature. If you do, draw a card.
Whenever another creature dies, target opponent loses 1 life and you gain 1 life. If this is the fourth time this ability has resolved this turn, transform Sephiroth.

Sephiroth, Fabled SOLDIER // Sephiroth, One-Winged Angel

Rottenmouth Viper

As an additional cost to cast this spell, you may sacrifice any number of nonland permanents. This spell costs {1} less to cast for each permanent sacrificed this way.
Whenever this creature enters or attacks, put a blight counter on it. Then for each blight counter on it, each opponent loses 4 life unless that player sacrifices a nonland permanent of their choice or discards a card.

Getting

Final Vengeance

As an additional cost to cast this spell, sacrifice a creature or enchantment.
Exile target creature.

Don't Have

Fear of Lost Teeth

When this creature dies, it deals 1 damage to any target and you gain 1 life.

Warehouse Tabby

Whenever an enchantment you control is put into a graveyard from the battlefield, create a 1/1 black Rat creature token with "This token can't block."
{1}{B}: This creature gains deathtouch until end of turn.

Torch the Tower

Bargain (You may sacrifice an artifact, enchantment, or token as you cast this spell.)
Torch the Tower deals 2 damage to target creature or planeswalker. If this spell was bargained, instead it deals 3 damage to that permanent and you scry 1.
If a permanent dealt damage by Torch the Tower would die this turn, exile it instead.

Vengeful Bloodwitch

Whenever this creature or another creature you control dies, target opponent loses 1 life and you gain 1 life.

Summon: Brynhildr

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Chain — Exile the top card of your library. During any turn you put a lore counter on this Saga, you may play that card.
II, III — Gestalt Mode — When you next cast a creature spell this turn, it gains haste until end of turn.

Spiteful Hexmage

When this creature enters, create a Cursed Role token attached to target creature you control. (If you control another Role on it, put that one into the graveyard. Enchanted creature is 1/1.)

Disturbing Mirth

When this enchantment enters, you may sacrifice another enchantment or creature. If you do, draw two cards.
When you sacrifice this enchantment, manifest dread. (Look at the top two cards of your library. Put one onto the battlefield face down as a 2/2 creature and the other into your graveyard. Turn it face up any time for its mana cost if it's a creature card.)