[Phantasm]

Originally Posted by Seneschal

Hmm, well, there wasn't a contest of wills, and what you're describing is definitely what the Ancient One does when first introducing the Mirror Dimension to Strange - creating a static, lingering gate which they both step through. However, during the New York Sanctum battle, just as the Zealots are about to destroy it with their big fireball, Strange kinda... drops the portal onto them. They don't even notice he's doing it (and they aren't moving, like at the beginning of the movie when the Ancient One opens a portal in front of them and they just run into it as it's hard to spot). I suppose something like Drifting could cover being able to move the portal after you Tunnel it, possibly engulfing people who don't move out of the way. But there has to be some way to make the effect resistable, absolute effects are very un-GURPS.

Not so much resistible, I think, but giving them an Active Defense (like Dodge) to avoid the tunnel may be the way to go.

IDHMBWM so I'm uncertain of the details, but instead of an Affliction you could perhaps place Weaponized (from Power-Ups 4: Enhancements) on World Jumper (Tunnel). The idea is to turn the ability into an attack that needs to be dodged rather than resisted.