Help, need to sanity check an NPC only feat that a PC has taken interest in. Quckly.

[Quertus]

Played less by legalize, and more by RAI, the "Minimize Spell" metamagic (which should be allowed to be used completely independent of modifying caster level IMO btw) is a homebrew I've used/seen on several of my/others' characters. And it's generally really underwhelming, with the occasional edge use of casting Fireball to kill fod, or for a con.

Even when the scope of the feat is extended to allow the caster to manipulate variables completely independently (ie, a 20th level Wizard can cast a fireball for anywhere from 5-10 damage, or 5d6-10d6 damage, independent of how well they penetrate spell resistance or how easy it is to dispel, it still isn't worth a feat for an optimizer¹.

The only time it even pings on an optimizer's radar is when you expand the RAI scope of the feat further, and say that the user of the feat can choose a "lesser effect" for any spell with multiple effects, where sometimes a "lesser effect" on (say) Confusion or Holy Word might actually situationally be useful - again, usually involving catching allies in AoEs, or for a con. EDIT: or allow it to be used as dynamically as lowering caster level; ie, applied for free on the fly. Or when you include a bonus, and allow, say, a 10th level caster to overcome SR as an 11th level caster if they minimize the Fireball damage to 5. Still generally horrible, IME, but at least it doesn't feel like a completely wasted feat.

¹ with the caveat that you explain that things like "cost calculations" are not one of those "independently set variables", and that, in fact, cost is calculated by the highest level used.