Toss in puffer, run in and slime, bubble out, rewind & repeat. Use your ult to lock down targets for your team to beat on, and Envenom anyone who gets low.

Icon	Level	Name	Description
	1	Bubble Breeze	Movespeed while invuln and unstoppable is pretty tough to beat, helps you chase down enemies or escape chasers. Must-have.
	4	Envenom	Hits hard and helps soften targets for your team or finish off someone who's low. Also gives you a nice ranged attack, which Murky doesn't have.
	7	Compressed Air	The bonus range on this synergizes well with Wrath of Cod, and makes it near-impossible for enemies to run away from your fish. They can still kill it, but that's time and attacks they're not using to kill you and your team. Basically, this ability makes your pufferfish a serious threat, especially when stacked with your future fish-related abilities. Slime Advantage can also be useful here, but 9 times out of 10 Compressed Air will be better.
	10	Octo-Grab	You can kind of play this one by ear. If your team is lacking in initiation or CCs, Octo-Grab is your friend. It also gives you a chance to get some skills off cooldown so you can get off a second burst. March of the Murlocs deals more damage and slows in an area, but most often enemies will just move out of the way. However if your team really needs some siege damage, it might not be a bad idea to swap over to MotM to help out. I'd almost always rather have Octo-Grab though, especially since you can grab someone on top of your pufferfish to force a hit.
	13	Wrath of Cod	The bonus damage you get from this is great, and forces enemies to deal with your fish or avoid it. You'll want to try to coordinate with teammates to get enemies CC'ed inside your fish AoE to deal the most damage, but don't feel bad about popping your ult to get a guaranteed hit from your fish.
	16	Slimy Pufferfish	Casting Slime when your fish lands beefs up the damage of your next Slime casts, slows enemies to make it harder to evade your fish, and triggers Wrath of Cod even if you can't get close enough to Slime them yourself. Win-win-win.
	20	Rewind	The key to the facemelting fish build, Rewind lets you pop your entire burst of damage TWICE. Throw a fish, Slime them, Bubble out, then Rewind and do it all again. You can also Slime->Puffer->Rewind->Puffer->Octo-Grab to force an enemy to get hit by two fish, which will almost always net you a kill. If it doesn't, pop your Envenom to finish them off.

Crowd Control

Murky has no health, so getting stuck in one place is lethal. To combat CC, constantly keep moving. Dodge in and out of combat whenever possible; Murky is a squishy commando, not a big fat tank.

Prolonged Fights

Murky doesn't do well trading damage, due to his small health pool. Even though you can dish out more damage than your opponent, whatever they hit you with takes a chunk out of your tiny hp bar. Try to hit and run whenever possible, and be watchful for low-hp enemies you can sweep in on and gank.

Soloing

Fish swim in schools for a reason. Murky is great at poking in damage and being hard to pin down and kill, but against multiple enemies he can easily be burst down before even spitting out one pufferfish. Try to stick with teammates whenever possible, Murky does his best work in teamfights.