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4) The cooldown on items is a bug in the ability coding for the items, I haven't yet found a solution, but I'm searching for one, so bare with me on that.
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You could try this:
In the item's ability list, put the active ability with cooldown on the top of the list, if a passive ability is on top of the list, the item won't display it's cooldown.
Example:
Holy Light (active ability)
Item Hero Stat Bonus (+3 strength)
Item Hero Stat Bonus (+5 agility)
I hope it helps, if you've already solved it, just ignore this. Damage Team
Survival is a brilliant map by the way