Viktor vs Kog'Maw

Poke with Hextech Ray (E), fired in the direction you choose: it hits every enemy in its line, and its upgrade adds an aftershock in its wake.

After Siphon Power (Q), land an auto within 4 seconds: it deals bonus magic damage, and the spell's shield covers you during the trade.

Place Gravity Field (W) in your target's path, then fire Hextech Ray (E): the field slows them, and if they stay in it for 1.25 seconds, they're stunned.

Glorious Evolution (passive) upgrades a spell every 100 Hex Fragments: Hextech Ray (E) to poke and clear, Siphon Power (Q) to survive, Gravity Field (W) to slow.

Place Arcane Storm (R) on grouped enemies: it follows the champions it just damaged on its own, and you can recast it to move it.

Engage when Bio-Arcane Barrage (W) ends: his attack range drops back to 500, and the spell has a 17-second cooldown.

If you can engage, go for him: with no dash or leap, Kog'Maw can only back off on foot, and Void Ooze (E) is his only slow.

Below 40% health, get out of range of Living Artillery (R): each shot then deals its max damage to you, and it reaches very far.

When he dies, move away from him: Icathian Surprise (passive) makes him explode 4 seconds later, dealing true damage to nearby enemies.