Passive - more health with more mana
Q - other abilities reset its cooldown and it scales with mana
W - A massive shield that scales with AP and maximum mana
E - A two second stun with AP scaling
R - Scales with AP and Mana, good luck getting away and it has a 2 second CD which means the Q is reset every 2 Seconds
You cant run from this, it has range, and everything scales with mana except E, meaning it has huge HP and with a seraphs, and RoA it has two huge shields that scale off of maximum mana.
Lichbane, Seraphs, RoA, Frozen heart and Iceborn gauntlet. You wont get away, it has huge amounts of HP because of the singed passive, it has huge amounts of armor because of frozen and iceborn, and it has rediculouse damage because of the 2 second ult CD reseting the Q CD and all of its abilities scale with mana which all of these items give.
Good luck.