Ideas for a better bruiser-mage and team-fighter Sylas (some abilities changes)

While lane phase Sylas is doing "okay", when it comes to team fights he seems to be struggling quite a lot. I wish he could be the TF leader like he kinda is in his lore. So, some changes on his abilities I'd make for achieving that would be: [warning, just ideas, guys, just ideas]

P: Petricite Burst Damage unchanged, heal from W moved to passive. He would heal 4/8/12% (based on lvl) of his maximum health for each time he procs his passive on a enemy champion. Goal is to make his passive feel more rewarding in TFs whenever it is 'procced'.

Q: Chain lash Unchanged.

W: Kingslayer Heal removed and placed on passive. Damage unchanged. New: Sylas lunges and strikes an enemy champion, stealing all his bonus armor and MR for 2/2.25/2.5/2.75/3 seconds.

E: Abscond / Abduct Unchanged.

R: Hijack New: Any time Sylas hijacks an enemy ult he increases the ult CD of the enemy champion that he copied by 10% (stacking up to 30%). This curse can be broken by participating on a killing over Sylas.