Ideally, it's great to have a whole mechanic or two that can do it
At the beginning of each end step, if a planeswalker entered the battlefield under your control this turn, put a 2/2 black Zombie creature token onto the battlefield
Between new set reveals, Lorwyn Eclipsed spoilers, and a staggering number of new Secret Lair drops, there was an awful lot to take in
If the Aura can't legally be attached to anything, it remains in its current zone
For each opponent who does, you draw a card and you create a 1/1 white Rabbit creature token
Turn it face up any time for its mana cost if its a creature card.) Whenever a face-down creature you control enters, draw a card