Change TCCY to this.

At 15 minutes, players are teleported back to the starting area with all cooldowns reset and health and mana reverted to 100%, and all terrain effects e.g. portals/aoe/traps on the floor, are removed. The game begins again but Battle Fatigue increases on all players by 2% every 12 seconds (e.g. 10% per minute) until healing no longer does anything.

The problem with the current TCCY is that the very thing that it's there to solve - unkillable kiting teams - are the very ones that gain most benefit from playing with it.

As far as I can see there's nothing about this that could encourage teams not to try to get a kill before that.
There's nothing that can benefit a team by not going for a kill.
There's no reason not to use your CDs to try to get a kill.
There's no reason to turtle, and turtle comps are actively at a disadvantage, promoting more fun gameplay.
Double/triple DPS comps are not benefitted, as those games rarely go on for 15 minutes and those that can last that long must be doing some serious offhealing, which is equally effected.

Thoughts?