Color Identity: B

Initial Card State
- All permanents on the battlefield (Soulstinger without a +1/+1 counter on it).
Steps
- Activate Bloodthrone Vampire by sacrificing Soulstinger.
- When Soulstinger dies, its undying ability and second ability trigger.
- Resolve the second trigger, optionally putting -1/-1 counter(s) on another creature.
- Resolve the Soulstinger trigger, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
- When Soulstinger enters the battlefield, its first ability triggers, putting a -1/-1 counter on it.
- Resolve the Bloodthrone Vampire ability.
- Repeat.
Results
- Infinite -1/-1 counters.
- Infinite creature ETB.
- Infinite creature LTB.
- Infinite creature sacrifice triggers.
- Infinite death triggers.
- Infinitely large creature until end of turn.
Bracket Tag
This combo has been estimated to be Oddball (Bracket 2-3+).