I agree with message of Samuel Weiss. My group plays in Planescape with all
the rules from S&P, C&T, S&M, Dragon magazines and much more. Of course,
some of us invented extra bonuses or combinations of them. But our beloved
Master said that if we, simple low-level characters can have these
superpowers (some of them invented by him personnaly), no one should be
surpsised by his orcs, goblins (one gobbo take very high-level Magic Missile
spell in face and still live) - and think what fiends can do... And all
strictly with rules...
If you do not want to make orcs even harder than they may be, remind your
player old, very long ago posted on one list : THERE IS NO OTHER DM THAN ME
IN MY GAME. If someone knows rules/combos better than you and loves them
more than pleasure of your sessions, kick him out.