How to win lane as Cassiopeia against Sion · 46.28% win rate (1,262 Emerald+ games, lolalytics, sampled July 2026) · Matchup data reviewed on patch 26.15
Poison shreds HP stacking — free DPS lane where only his engage cooldown deserves respect.
Track: Sion's Q — Decimating Smash (10–6s cooldown). Charged knockup — break the channel or sidestep the slam.
Read from Cassiopeia's seat: which stage windows this plan plays for against Sion.
This is Cassiopeia's own plan; across 1,262 pooled games the lane is leaning Sion.
| Stage | Favoured | Why |
|---|---|---|
| Level 1 | Even / skill | At 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 2 | Cassiopeia | With 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 3 | Cassiopeia | Your 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 4-5 | Cassiopeia | Ranks 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 6 | Cassiopeia | Petrifying 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 item | Cassiopeia | With 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+ items | Cassiopeia | Your single-target shred melts his tank build faster than his E poke matters; only a fog flank or surprise R engage threatens you now. |
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 Decimating Smash 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 Roar of the Slayer's 12s armour-shred poke can't out-trade your ramping DoT chip.
Pooled Emerald+ win rates from Cassiopeia's side, sampled July 2026.
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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Sion, slightly — Cassiopeia wins 46.28% of 1,262 games; winnable with the right plan.
Mostly — Sion has a small statistical edge (53.72% win rate), but execution decides this lane far more than the pick does.
No — if anything Sion has the slight edge (Cassiopeia wins 46.28%), though it stays close.
Cassiopeia takes Conqueror on the Precision tree with Presence of Mind, Legend: Haste and Last Stand, and Sorcery secondary (Manaflow Band and Transcendence) vs Sion.
Start Doran's Ring + 2 Health Potions and back for Tear of the Goddess + Dark Seal (≈800g). Build Seraph's Embrace / Liandry's Torment first, then Rylai's Crystal Scepter, with No boots — bank the gold into Zhonya's earlier.
Playing the other side? Sion vs Cassiopeia guide →
All Cassiopeia top lane matchups →
More Cassiopeia top lane matchups: vs Sett · vs Shen · vs Singed · vs Swain · vs Sylas · vs Tahm Kench