I house ruled Psychic Guidance in my Felltower game, changing the one in Dungeon Fantasy 11: Power-Ups.
I like the concept, but I don't like the execution. Basically, replacing the Innate Attack skill with the Missile spell itself does two things:
- it makes the points in Innate Attack largely wasted, especially since PC mages tend to specialize in one or two spells. This makes Psychic Guidance critical instead of a good value, and makes the point investment in Innate Attack useless.
- it makes the Missile spell skill extremely valuable, as it improves your accuracy and the power/discount on the spell, too.
I used to play in my 1st edition GURPS game that you rolled against the Missile spell skill to hit, so I know what I'm looking at here from years of play. It's ugly - you get high Missile spell skills to get cheap and/or free missiles, and that also increases accuracy to a high degree.
Instead, what I did is this:
- Psychic Guideance lets you add your Magery to your Innate Attack skill when throwing that spell.
For example, a basic DF Wizard with DX 12, IQ 15, and Magery 3 and Innate Attack (Projectile) @ DX+2, this means going from a 14 base skill to a 17 for a 1 point perk investment.
"Mystic Guidance" would be a good name for this, actually, if you're inclined to name it.
Alternately, you can just base the Innate Attack for that specific spell on IQ, no Magery bonus, and make it purely psychic and not mystic guidance. In that case, the effect on a basic DF wizard is the same - they jump from skill 14 to skill 17 for one point (IQ+2 instead of DX+2 when using that spell.)
In either case, you still benefit greatly from the perk, and benefit greatly from improved Magery or improved IQ, and your basic skill isn't made irrelevant. It's a no-brainer choice for a missile spell user, but it takes advantage of the underlying skill and the generous ability of floating to a new stat and/or getting Talent bonuses to skills that 4e allows.