When Gwen Stacy enters, exile the top card of your library. You may play that card for as long as you control this creature.

2URW: Transform Gwen Stacy. Activate only as a sorcery.

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Ghost-Spider

Flying, vigilance, haste

Whenever you play a land from exile or cast a spell from exile, put a +1/+1 counter on Ghost-Spider.

Remove two counters from Ghost-Spider: Exile the top card of your library.
You may play that card this turn.