Cassiopeia

Strengths

Use Twin Fang on poisoned stationary targets like monsters and units stunned by her Petrifying Gaze for maximum damage.
Lead your enemy when targeting with Noxious Blast to ensure the hit.

Passive · Serpentine Grace — All Move Speed bonuses are more effective on Cassiopeia.
Q · Noxious Blast — Cassiopeia blasts an area with Poison after a brief delay, granting her increased Move Speed if she hits an enemy champion.
W · Miasma — Cassiopeia releases several clouds of poison, slowing, grounding, and lightly damaging enemies that pass through them. Grounded enemies cannot use Movement abilities.
E · Twin Fang — Cassiopeia lets loose an attack that deals increased damage to Poisoned targets and heals her for a percentage of the damage dealt. If the target dies from this attack, Cassiopeia regains Mana.
Ultimate · Petrifying Gaze — Cassiopeia releases a swirl of magical energy from her eyes, stunning any enemies in front of her that are facing her and slowing any others with their back turned.

A suggested 5-lane lineup built around Cassiopeia, based on hero partnerships and role synergy — not win rate.