you also need to stop acending ur items, its really not going to benefit you much at all in early game, its more of an end game thing you want to be doing to 6 star items. and try bring the quaility of ur items up and aim to gear everyone in 5 star items, dont waste ur time maxing out 3 star and 4 star items, you will only hate ur self in the future for doing this i promise. and as kram said if ur speed on artak is still at 111 then this is pretty bad, aim for around the 160-180 speed range for now at least on all champions. and if you have not done this already aim to acend ur champions instead of acending ur items because this will unlock ring/amulet/banner slots on ur champs which makes a much bigger difference.
also if ur struggling to kill the dragon its probably because ur kael has no accuracy at all and cant land his psn debuffs ( psn is one of the best ways to take it down ) but if ur kael is sitting at 50 accuracy there is no way hes going to be landing those much needed psn buffs,you should be aiming for more around the 150-200 accuracy range on him for now.
as for ur stagknight pull he is a fantastic champion and probably worth 6 star, he may not be as useful to you in dragon with the current team ur using but he will certainly be great in other dungeons and other content for you.