victors q with your cdr runes and mastery's has only a 3 second cool down at max rank and is a free ghost that lasts for it's cool down. this paired with rylai's makes you able chase or escape from almost any champion. a 35% slow and speed up is very strong and on top of that your ult and lazer get a 15% slow as well and you have the gravity field if all else fails.

if you get spell vamp early you can gain hp very fast by poking the enemy mid with your q because you gain health and a shield so if done fast you will be able to shrug off any return poke and this is a lot easier with the power/rylais combo.

also if you already have lots of damage on your team but no initiator you can do that job with this build because of how tanky and mobile you get off spamming your q and the ult's short silence mixed with your gravity field is bound to lock down at least one champion.

also you can save a lot of mana this way because you will be using your Q for CC,damage, defensive steroids, moment speed, and hp regeneration. this makes it so you only have to use your other ability's in team fights or to face roll in a difficult 1v1.