Skarner isn't ass but he's a little dependent on a team. His issue is that the way his Q works he just perpetually slows someone so you can get the kill fairly easily but it just takes a decent amount of time. They should slightly increase both the cooldown and slow on his Q. It's really his only problematic skill as far as balance goes. His E's heal is borderline OP in top lane since he can heal for like 150 every 8 seconds and his mana costs are super low as well.
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~Acting on Impulse~
Black Turtle still didn't MAJORA'S MASK