Feat: Thoughtform Summoning
You can create a prototypical creature from the depths of your imagination instead of calling one from elsewhere. Whenever you summon a creature, you can choose to instead create a psychic construct of that creature. This grants it resistance to physical damage equal to half its level, weakness 5 to force and mental damage, and the ability to pass through enemies' spaces without needing to Tumble Through (though it can't end its turn in an occupied space).