Dominion Saboteur dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it. As it enters, choose to have it copy a creature you control that has a +1/+1 counter on it, so
Dominion Saboteur will also enter with a +1/+1 counter on it.
Resolve the
Bloodthrone Vampire ability.
Repeat.
Results
Infinite creature ETB.
Infinite creature LTB.
Infinite creature sacrifice triggers.
Infinite death triggers.
Infinitely large creature until end of turn.
Metadata
Bracket tag
ExhibitionBracket 1+
For any deck
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1 · Exhibition5 · cEDH
Bracket tags are estimated from the cards and results of each combo, as a guideline rather than a strict classification.