Gangplank vs Gnar

Build a chain with Powder Keg (E): detonate the keg farthest from your opponent, and each keg whose area touches the previous one explodes too, all the way to them.

Last-hit minions and pop kegs with Parrrley (Q): a kill with the shot gives bonus gold, and so does a kill from a keg it sets off.

Save Remove Scurvy (W) for a key CC rather than for healing: it cleanses all CC on you, on a 22 to 14 second cooldown.

Cast Cannon Barrage (R) anywhere on the map to help a fight or cover an objective: each wave of cannonballs slows and damages in the area.

Take your trades when he's Mini Gnar with little Rage Gene (passive): he then has no stun and none of Mega Gnar's defenses.

Dodge Boomerang Throw (Q): it slows you, and if he catches it on the way back, its cooldown drops.

Take short trades: on every third auto or ability that hits you, Hyper (W) adds damage based on your max health.

Stay away from walls against Mega Gnar: GNAR! (R) knocks back every nearby enemy, and those who hit a wall are stunned.