The Master, Formed Anew | Bloodflow Connoisseur

(and two other cards)

Persist Creature

Undying Creature

The Master and
Bloodflow Connoisseur on the battlefield.
Persist Creature and Undying Creature in exile.
Both the persist and undying creatures are in exile with at least one takeover counter on them.
The Master on the battlefield as a copy of either the persist or undying creature.
The Master does not have a +1/+1 counter on it if it is a copy of the undying creature, or a -1/-1 counter on it otherwise.

Activate
Bloodflow Connoisseur by sacrificing
The Master.
When
The Master dies, if it was a copy of the undying creature, its undying ability triggers, returning it from your graveyard to the battlefield as a copy of the persist creature with a +1/+1 counter on it.
Otherwise, if
The Master was a copy of the persist creature, its persist ability triggers, returning it from your graveyard to the battlefield as a copy of the undying creature with a -1/-1 counter on it.
Resolve the
Bloodflow Connoisseur ability, putting a +1/+1 counter on it.
Repeat.