Found this when messing around with engineering, dont think its been posted yet so here you go
First put hand-mounted pyro rocket(engineering) on 2 pairs of gloves
Equip first pair and use the rocket on a target
Swap to 2nd pair and use the below macro
/use *name of 2nd pair of gloves*
/cast *name of spell*
(Keep spamming the macro)
You'll have no gcd on instant cast spells for 1 minute, not that great but as a mage I can still kill someone with deep freeze > ice lance spam
Maybe someone else can find a use for it.