But you apply prison at distance and from safety, and execute the combo with your champions in normal positioning, to combo with trail, sixul should be behind the enemy.
Of course. And that is a fair argument, but this guy already is going to have a bunch of ways to spend AP. 5 AP on top of the 3 AP for Set Ablaze and the AP for the items on UP 2 is going to leave him really AP starved, particularly if he wants to attack every so often.