Cassiopeia generates a stack of Aspect of the Serpent once every 6 seconds (10 times per minute) and for every second that an enemy champion is poisoned by her abilities, up to a maximum of 500 stacks.
Cassiopeia empowers herself in different ways when she reaches certain milestones:
100 Stacks:+ 5% AP, and Twin Fang now heals for 6 / 8 / 10 / 12 / 14 / 16(+ 6% AP).
The facing direction of champions whose abilities/animations cause them to spin is always the direction they are moving in. In the event of abilities that cause the champion to spin on the spot, such as Katarina'sDeath Lotus, it will factor the direction they were facing on-cast.
Lucian is facing in the direction he is moving during The Culling, not the direction his model is facing.