
Void Battery
+250 Max Energy
+3 Energy Recharge
Tip: Energy is needed to use your abilities. 

Energy Battery
+100 Max Energy
+1.5 Energy Recharge
Tip: Energy is needed to use your abilities.  


Chronograph
+15% Cooldown Reduction
+0.75 Energy Recharge
Tip: Cooldown speed increases the speed at which your abilities come off the timer. 

Hourglass
+7.5% Cooldown Reduction
+0.25 Energy Recharge
Tip: Cooldown reduction the time it takes for your abilities to come off the cooldown timer.  
This does stack if you buy more than one right?
All item stats, even the weird ones like "cooldown acceleration" and "weapon lifesteal" stack.
But, if you read DeadMan's post above, you'll see why buying the second one will be less effective than the first.
COOLDOWNS in Vainglory are BASE COOLDOWN/1 + % amount COOLDOWN ACCELERATION. The Base Cooldown is Divided by 1 + % amount cooldown acceleration. With 1 Clockwork all your cooldowns will then be BASE ABILITY COOLDOWN /1 + .5, or COOLDOWN/1.5. 2 Clockworks will divide your Cooldowns by 2. 3 will divide your cooldowns by 2.5.
An example of this is at max rank Krul's ult has a 50 second cooldown. With 1 Clockwork his ult's cooldown is reduced to 33.3 seconds. Possessing 2 clockworks would divide his cooldowns by 2, which means he will have a 25 second cooldown on his ult.
This should not be confused with COOLDOWN REDUCTION, which other popular MOBAs use (Cough League), which is hard capped at 40% and if you had 100% COOLDOWN REDUCTION would in fact reduce your cooldowns on all abilites to 0 where 100% COOLDOWN ACCELERATION only divides your base numbers by 2.
Thanks to whomever posted this on the forum originally.