I can't quite make out what direction you are trying to take this concept in. The temporal gate idea, while not bad doesn't feel fully fleshed out; nothing should really appear on the battle field except for pets or turrets, things you place yourself. The idea of quickening DoTs is good, but it would need to be implimented in a way so that it doesnt become a chore to use. Also, while the idea for a Slow, Stop, or even Haste is good, we know that utility like these have been fazed out of the standard kits, and moved over to role actions, so they sorta are dead space at the moment.

Additionally, while AST has lost some of it's Time Mage identity, it still has the aesthetic, especially with Gravity and Lightspeed still being a thing.

What I personally would suggest is to try and formulate a mechanic that gives the illusion of time management, but still fits within the confines of our current game. I think working around Quicken is a good start.