[@floodtalon] IF it works like you're saying, then you can summon your Gates, BUT they won't absorb Jorm's attack, because the attack you're trying to teleport/portal/what-have-you away, is also within the field, it's not from outside. Unless you're ruling that the rules are different for living and non-living, which just introduces more dumb problems (like Victoire or Jorm using portals and throwing attacks through them to blow you up from the inside Traveller Meson Cannon/Schlock Hyperspace Gun style).

And wouldn't that mean that Jorm should have been able to teleport to inside the field from outside of it?

If the thing just blocks dimensional shenanigans within its range, it makes sense. If you tack on a whole bunch of wierd convoluted conditional restrictions explicitly to make one fight last longer that you are going to lose regardless, that's dumb. Especially when by doing so you compromise what the Dimensional Anchor was originally supposed to have been designed for so that it better counters someone you could have by no means predicted.