Vivi Ornitier | Agatha's Soul Cauldron | Geralf, the Fleshwright

(and one other card)

Cast
Clockspinning with buyback by paying ({3} magic symbol) ({U} magic symbol) .
Geralf triggers, creating a 2/2 Zombie Rogue creature token.
When the Zombie Rogue enters the battlefield,
Geralf's second ability triggers, putting a +1/+1 counter on the Zombie Rogue for each other Zombie that entered the battlefield under your control this turn.
Resolve the
Clockspinning spell, returning it to your hand.
Activate the Zombie Rogue using Vivi's ability by paying ({0} magic symbol) , adding an amount of ({U} magic symbol) equal to its power.
Repeat.

The mana cost assumes you've had only one Zombie enter the battlefield this turn. If you've had two or more, the cost becomes ({3} magic symbol) ({U} magic symbol) instead.