Spell Tinker

Level 16

Concentrate Wizard

You’ve learned to alter choices you make when casting spells
on yourself. After casting a spell on only yourself that offers
several choices of effect (such as resist energy, spell immunity,
or a polymorph spell that offers several potential forms), you
can alter the choice you made when Casting the Spell (for
instance, choosing a different type of damage for resist energy).
However, your tinkering weakens the spell’s integrity, reducing
its remaining duration by half.

You can’t use this feat if the benefits of the spell have already
been used up or if the effects of the first choice would persist in
any way after switching (for instance, if one of the choices was
to create a consumable item you already used, or to heal you),
or if the feat would create an effect more powerful than that
offered by the base spell. The GM is the final arbiter of what
Spell Tinker can be applied to.