When a creature with undying dies, the creature goes to the graveyard, and the undying trigger brings them back into play when the ability resolves. This means that because creatures go to the graveyard, both leaves-the-battlefield abilities and enters-the-battlefield abilities will trigger.

For example, if you cast Undying Evil on a Wurmcoil Engine before it dies, two abilities trigger when it hits the graveyard (it has to hit the graveyard for undying to trigger in the first place). The Wurmcoil Engine’s normal “dies” trigger and the undying ability both happen, and you end up with the two Wurm tokens and a 7/7 Wurmcoil Engine that will give you more tokens the next time it dies!

Similarly, when Geralf’s Messenger dies (with no counters on it), undying will return it to play (tapped, because the card says so), with a +1/+1 counter. Because it entered the battlefield again, its enters-the-battlefield ability will trigger, and the opponent will lose 2 life.

The other reason it’s important to know that undying creatures spend at least a little time in the graveyard is because you get a chance to respond to the undying trigger before it returns the creature to play. That means you can cast Purify the Grave or Surgical Extraction on that creature so it can’t be returned when undying resolves. When it changes zones, it becomes a new object and the game doesn’t associate the exiled card with the card that was in the graveyard.

Today’s Rules Tip written by
Ronny Alvarado, Level 2 Judge from Houston, TX (congrats on passing Level 2!)