Skarner

Skarner rides on one simple, terrifying idea: Impale fully disables a target and lets you drag it wherever you want. No ability on the roster removes a player from their own fight for that long. Everything else in the kit exists to get you into range: Crystalline Exoskeleton grants a shield and a speed burst, Fracture slows from a distance and heals you back, and Crystal Slash hits everything around you on a short loop.

His real engine is his Energize passive, which cuts every other cooldown down every time he lands a basic attack, and even more so against a champion. A Skarner who stays on top of his target spins his kit dramatically faster than a Skarner chasing from behind. He's a character built on sustained pressure rather than burst: he doesn't hit hard in one shot, he keeps grinding and turns a good read into a kidnapping.

His strengths are the reach of his crowd control and his ability to isolate. Catching a carry at the right moment wins a fight without dealing any damage, and moving during the disable lets you pull them out of their support's protection. Crystalline Exoskeleton solves the problem every melee-contact character has: actually getting there. Finally, Crystal Slash makes him one of the best camp clearers in the mode, with a cooldown so short it nearly loops on itself.

His weaknesses are severe. His ultimate has short range: you have to physically walk into the enemy front line to use it. Without it, Skarner threatens no one and his raw damage is unremarkable. His mana cost runs high if you spam Crystal Slash, and he has no escape once his shield is spent. And a target immune to crowd control makes your main button worthless.

In the jungle, max Crystal Slash first: it drives your passive, clears camps, and its charged second cast slows, which stands in for real crowd control before level six. Aim to hit multiple units at once to keep the charge running through the whole camp. Your clear is fast, use it to hit level six before the enemy jungler, that's the only level that matters for you.

Before your ultimate, ganks live on Fracture to slow from range, then Crystalline Exoskeleton to close the gap. Activate the shield before entering the lane, not after: it's your move speed, not your survivability, that decides the gank. Past level six, flip the whole approach: come in from the side opposite the enemy's retreat, impale, and drag the target toward your own tower instead of trying to kill it on the spot.

Level six is your one big spike, and it's brutal. Before it, you're a decent jungler with no real kill threat; after, you're the character who can pull any player off the map long enough for four allies to finish the job. Build your whole game around that swing, including holding a play on the most extended lane in reserve.

The second spike comes from cooldown reduction and mana. Skarner benefits more from cooldown reduction than anyone in the mode because it stacks with his passive: every basic attack pulls your next ultimate closer. A high-cooldown-reduction Skarner can impale twice in back-to-back fights, which is a difference in kind, not degree.

You're not the front line, you're the hook. Sit on a flank, wait for the enemy's crowd control to land on your tank, then dive in for the carry. The question before you press the ultimate isn't 'can I catch him,' it's 'where am I taking him': always pull toward your team and away from his, it's the drag that wins the fight, not the impale's own damage.

While dragging your target you're effectively immobile and completely exposed. Your team needs to be ready, or you're handing over a free death. After the ultimate, stay on top of the target instead of backing off: your passive only spins if you're hitting, and your shield plus slows make you a permanent nuisance. Against a team with a cleanse effect, force it to be spent elsewhere before you engage.