Did a couple of these over on the WizO's boards myself so I thought I'd share some feedback
Felix said:
snip
- Minimize Spell Metamagic:
All variable, numeric effects of a spell modified by this feat are minimized. A minimized spell deals minimum damage, cures minimum hit points, affects the minimum number of targets, etc. For example, a [Minimized] Disintegrate will deal 2/level damage after a failed fort save, remove the target, leave his stuff, and be equivalent to a 3rd level spell. Saving throws and opposed rolls are not affected, nor are spells without random variables. A minimized spell uses a spell slot three levels lower than the spell's actual level.
3 levels lower is way too much. I would go with 2 lower, but probably 1 lower is best.
Felix said:
- Depower Spell Metamagic:
A [Minimized] spell will deal 50% less of all variable damage than normal and use a slot two levels lower, minimum 0-level. A [Depowered] Melf's Acid Arrow will deal 2d4 - 2d4/2 acid damge each round (minimum 1) and use a 0-level spell slot.
Think you have a typo there in the first sentence second word

I would go with the suggested half damage period for 2 levels lower, but as is only 1 level lower.
Felix said:
- Contract Spell Metamagic:
The range of a [Contracted] spell is reduced by 50%, and uses a spell slot one level lower than normal. A long range spell (400ft+40ft/level) would become (200ft+20ft/level).
Wouldn't use this one at all, -- way to abusable. I mean, how many times do you actually see a fireball cast a max range anyway? & multiple applications to the same spell, well you get the idea
Felix said:
- Reduce Spell Metamagic:
The area of effect of any burst, emanation, line, or spread-shaped spell is reduced by 50%. For example, a [Reduced] fireball spell will deal 1d6/level damage in a 10-ft radius burst. A [Reduced] Spell uses a slot three levels lower than the spell's actual level.
This one again is too lowered. I'd make it only 2 levels lower, if not only 1.
Felix said:
- Breif Spell Metamagic:
The Duration of a [Brief] spell is reduced by 50%. A spell with a duration of concentration, instantaneous, or permanent is not affected by this feat. A Breif spell uses up a spell slot one level lower than the spell's actual level.
This one is fine IMO.
Felix said:
Of course, you can also apply normal metamagic feats to these spells. So you could cast a [Breif, Silent, Still] Charm Person as a 2nd level spell, and have just enough time to slip by the guard without wasting the unnecessary duration.
Actually this is one of the rules I've suggested as a possible no no for these types of feats because where you actually run into the most problems is when you use metamagic & anti-metamagics together. A simple rule not allowing the combination solves almost any problems with these reductions.
Allow me to elaborate:
I want to cast a quickened spell of the highest spell level I can cast. Normally not possible, but with these feats, it's easy & I get almost the exact effect in many cases, especially if I use Reduce & Contrast (as you've written them) to target a foe in melee. Not a good thing IMO, so that's where I'm coming from with that rule & the advice above.