As sylas, His Ultimate R is completely dependent on the enemy team comp. If the enemy has lacklustre ultimates, Sylas won’t be able to do much.

If used improperly, his W can get him killed due to him getting displaced to another location. If the enemy purchases Grievous Wounds, they can easily counter this heal by a good amount.

Proper vision placement can ruin his chances of being able to flank the enemy team with his E. He won’t be able to effectively impact a fight when he can’t flank the enemy team. As sylas, His ultimate R is completely dependent on the comp enemy team. If the enemy has ultimate lacklust, Sylas will not be able to do much. If he is misused, his W can have him killed because of his move to another place. If the enemy buys Grieve Injuries, they can easily counter this healing with a good amount.