I've had a chance to look at them now, and I think they're pretty balanced, as they're limited in scope, area and/or range. The biggest limiting factor for the one you mentioned above is it's range...so if you hang on to a Melf's acid arrow you may be able to do throw a 2d6 acid orb at will, but it's limited to a range of 10 feet, which is a bit close for my taste.Nonlethal Force said:There is a reserve feat (for example) based on acid. Essentially, it allows a caster who still has an uncast acid spell of X level to throw Xd6 (I think) at will without giving up the spell in question.
So, say I am a 3rd level character and have Melf's Acid Arrow memorize or I am a sorcerer with Melf's Acid Arrow known and a 2nd level spell slot still uncast. My caster can toss 2d6 acid orbs till the cows come home every level until Melf's Acid Arrow is cast (in the case of a wizard) or until all the 2nd level spell slots have been used for the day (in the case of a sorcerer).
Nice feats, huh? I think they give too much power to an already powerful class. Keep in mind, I only got a look at them today - I don't have the book yet in front of me.
I'm not so much worried about the power vs. Warlock aspect as I am in the additional power of the spellcaster increasing, though.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.