I still like 3v3 over 5v5 and i think its time for semc to change it like they wanted before but probably being the only mode made them afraid of any change !
So what i think is this
remove crystal sentry elimination and make him with his prev attack range , and make the team taking it get a buff like ghost wing buff , and make his team (the defenders get some kind of buff while around him) , so defenders gets a kind of buff around and once its taken the buff get stronger and move to enemy team .
kraken capture bar start moving once kraken spawn with different acceleration , so the kraken getting captured by a neutral force and teams need to act , steal it from the neutral force or fighting each other and stop the capturing , it resets whenever somone attack the other team , after 2 minutes of no one capturing , the kraken capturing bar will get rapidly moving up whoever get last hit get it .
last turrets cant be pushed without kraken , the vain defend the last turrets from minions and heroes but it stops against kraken , and the kraken get faster movement against the last turrets to prevent killing him before reaching them .