Whenever you attack with one or more Zombies, draw that many cards, then discard that many cards. You gain that much life.
{2}, Exile two cards from your graveyard: Create a tapped 2/2 black Zombie creature token.
Varina's first ability counts the number of Zombies you attacked with, even if some of those Zombies leave combat before the triggered ability resolves.
13 Jul 2018
The number of cards you discard and the amount of life you gain are both equal to the number of Zombies you attack with, even if you draw a different number of cards somehow.