Ornn

Ashe perma-slows Ornn with Volley (W) plus Frost Shot autos. Volcanic Rupture (Q) terrain takes time to set up, Searing Charge (E) has no dash range, and Call of the Forge God (R) cannot reach her if she kites with her support.

Fiora's Riposte parries Searing Charge and stuns Ornn instead, cancelling the whole Brittle combo before it starts. Her Duelist's Dance vitals then deal true damage every few seconds, and Ornn's stacked armor does nothing against it.

Ornn cannot disengage from Flawless Duet (E) stun and has no answer to repeated Bladesurge (Q) resets through the wave. Volcanic Rupture (Q) terrain is sidestepped by Q dash, and Call of the Forge God (R) charge is interrupted by Vanguard's Edge (R) wall pin.

Counter Strike stuns him on top of Jax and Volcanic Rupture (Q) is the only ranged threat he has — Jax dodges Searing Charge (E) commit, stuns on the recast, and stacks Relentless Assault on a target with zero disengage past level 6.

Kayle's Starfire Spellblade (E) on-hit deals percent-health magic damage that ignores Ornn's armor stacking. From level 6 Divine Ascent (P) makes her ranged with +350 attack range, which puts her outside Volcanic Rupture (Q) entirely.

Volcanic Rupture (Q) and Bellows Breath (W) are both short-range — Rhaast's Reaping Slash (Q) max-HP damage chunks Ornn's tank HP through resistances, and Blade's Reach (W) knock-up cancels Searing Charge (E) commit. Call of the Forge God (R) cone is dodged by Shadow Step (E).

Kennen's Thundering Shuriken (Q) pokes from 950 range, outside Volcanic Rupture (Q). Electrical Surge (W) adds a mark, and the third mark from any of his abilities stuns Ornn out of the Searing Charge commit.

Volcanic Rupture (Q) and Bellows Breath (W) both have wind-up frames Rumble can interrupt with The Equalizer (R) slow zone. The magic-damage kit ignores Ornn's armor stack from Living Forge, and Electro Harpoon (E) slows during his Searing Charge (E) wind-up.

Hijack copies Call of the Forge God and gives Sylas a two-cast long-range knock-up the moment he reaches level 6. He fires the first cast from fog of war, then knocks-up the same line again on recast, controlling the entire teamfight from outside his usual short range.

Teemo sits at auto-attack range and lets Toxic Shot chip Ornn's HP every wave, faster than Doran's Shield can regenerate it. Blinding Dart then blanks his basic attacks, so he cannot farm the wave back or land a Grasp of the Undying hit while the poison keeps ticking.

Black Cleaver plus Crushing Blow (Q) armor shred deletes Ornn Living Forge passive masterwork resistances, so even when he survives the all-in his team-wide passive value drops. Warrior Trickster (W) turns Wukong invisible as Call of the Forge God (R) lands, missing empty ground.