Fighting anything with a THAC0 of AC-18 'like say' a DeathKnight and your 6-pack party is spell drained & @ 1/4 max hp and each is jacked with AC-19 gear, Even With Haste, Makes for one Long, long day of battle. Then I bought some 20 sided dice to upgrade my 1d12's...
Then There's G.U.R.P.S where you can chuck most anything you want into a character and it can roll with it.
Little Known Fact, Battle Tech does have a whole RPG section that has nothing to do with piloting tanks & mech's. Of 'Course, I've Always Wanted to put a high level Pison or a Caster as a rider in a cockpit, but no DM seems interested in letting 'A Connecticut Yankee in king Arthur's court.' ;)