I got rushes as a low level (still low level, but my highest is only level 23) but after that I like to stck to battling out the quests and demons on my own, not by rush. For one you actually gain large amounts of ep that way. I got to levl 4 from level 3 from andariel, duriel, and meph. and I was half way to lvl 4 ne wayz.