Cassiopeia vs Sion — Top Lane Matchup Guide

How to win lane as Cassiopeia against Sion · 55.35% win rate over 159 Emerald+ games · Updated 2026-07-27

Verdict: Cassiopeia is favoured — Cassiopeia owns 6 of the 7 game windows. Cassiopeia wins 55.35% of games vs Sion in top lane (159 Emerald+ games analysed).

Favour timeline — who owns each window

StageFavouredWhy
Level 1Even / skillAt level 1 you have one ability and no poison stacked, and a charged Q can knock you up before you ramp — last-hit at range and never trade into the charge.
Level 2CassiopeiaWith Q + E online you prime with Noxious Blast and chain Twin Fang while he eats the tick, and he has no dash or blink to leave the poison cloud.
Level 3CassiopeiaYour full Q-to-E chain plus Q move-speed kiting comes fully online against a slow, single-target body that can't escape it.
Levels 4-5CassiopeiaRanks in Q and E let you chain Twin Fangs on a primed Sion; his ranged E shield-break can't out-sustain your DoT, and Miasma's slow stalls any walk-up.
Level 6CassiopeiaPetrifying Gaze stuns his charged Q wind-up or executes him the moment his W shield drops — every trade tips into a kill for you.
First itemCassiopeiaWith Malignance or Liandry's online your Q+E chip out-paces a Grievous-less tank who has no sustain to heal the poison off.
Two+ itemsCassiopeiaYour single-target shred melts his tank build faster than his E poke matters; only a fog flank or surprise R engage threatens you now.

Early game (levels 1–5)

Level 1 is your only soft spot — you have a single ability and no poison stacked, so don't walk up to a Sion holding a Q charge; just last-hit at range and respect the knockup. From level 2 this becomes your lane: drop Noxious Blast on his feet, let the poison tick, then weave Twin Fang for the refunded-cooldown nuke and peel off on your Q speed buff. He's a slow, immobile, single-target body — exactly what Twin Fang eats — and his ranged E shield-break poke can't out-trade your ramping DoT chip.

Read the rest of this matchup

The full Cassiopeia vs Sion report continues with the mid-game plan, the late-game and teamfight plan, every power spike to play around, and the win conditions for both sides — plus cooldown tracking and the live enemy-jungle tracker inside the app.

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Playing the other side? Sion vs Cassiopeia guide →
All Cassiopeia top lane matchups →