I found dominion lacking any real sort of tactics I've found it pretty easy to hold mid on my own even against three people long enough for back up while my team maintains A and C and run around ganking

Maybe for a new mode a more tactical and lengthy siege where attacker and defender are actually attacking and defending

Attackers have a set amount of lives or time to siege a castle or keep in 3-4 stages the gate, the walls, the court yard and the throne room
players have to push minions capture 2-3 points break the defenders kill them then push up
defenders have to do the same to push the attackers out in the 3-4 stages
Once in the throne room attackesr have to break and kill the defenders one last time to win.

this opens up a longer matches (10 minutes is kinda meh) and more tactical gameplay