Does enchanter haste stack with my mages burnout line or is one cancelling the other out? When I caste both on pet, they both show up in pet buffs.
They are both Increase Attack Speed, but different slot numbers is why they both stick. Haste doesn't stack of the same type, so you only get the best of the Increase Attack Speed buffs. Other portions of the buffs may still apply also (stats, procs, etc.) There's overhaste (Increase Haste v3) that stacks and adds to normal haste buff. If I remember correctly, most Mage pet hastes are better than level equivalent Enc hastes, but there certainly are higher Enc buffs that can be better, depending on levels. Some links: How to read Spell Data information and how to determine sticking and stacking Old but still good list: List of Overhaste Spell Effects Yther Ore.
Magician pet haste tops out relatively early on at 85%. The enchanter combined haste buffs top out at 68%, and Wondrous Rapidity at 70%. So, no, it's not worth casting enchanter haste on a mage pet, although high level haste on a low level (well under 70) pet can't hurt.
The extra stuff that high level Chanter haste adds is nice for melee characters, although I haven't checked how well it stacks on pets.
Item haste and Spell haste top out adding 100%, so base haste of 100, plus an item adding 32 (or more) plus enchanter haste of 68, would be total of 200 and max (without any over haste). Enchanters cast the best melee haste in game at higher end what with the crit bonuses, which is one more reason to get the AA pet affinity at level 65, Spell haste is cast by Clerics and helps casters get off heals and nukes that little bit quicker.
