Game Mechanics: Instant Cast Items and the Spell Gem Refresh Timer

[Kainzo]

When I was playing in Classic, many moons ago. I remember Jboots were very coveted for casters. Not especially for the run speed but more importantly for the effect the instant cast item had an effect on the global refresh time on the spell gems.

Whenever a caster would cast a spell, normally it would take 1.5-2 seconds for the gems to come up so they could cast yet again. However, if the caster were to use an instant cast item - they would be able to "instantly" refresh the cool down of the spell gems which made them able to cast a second faster.

I tested this last night as soon as I picked up my Jboots (fuck you AC and thanks Splinko for camping with me) that it indeed did not lessen the global cool down.

Any thoughts on this?