Marchesa gives everyone a +1/+1 when they attack the highest-life player, and anything that dies with a +1/+1 on it comes back at the end step.

Undying brings creatures back if they don't have a +1/+1, and gives them one.  Great automatic loop with Marchesa.

The next best thing: Unleash gives the option of +1/+1 on ETB, but they can't block. This automatically makes them come back to life with Marchesa in play.