On the topic of Skarner (mainly his passive)
The rest of his kit is fine. It's wonderful to play, both as and against. His poke is mediocre at best, but allows him to engage properly. He can chase down targets rather well, and can be sticky. 1 v 1 potential is nice, and he plays his role as a diver or skirmisher quite well.
Passive though? In my opinion, it's one of the only passives in the game which causes more bad than good. The enemy knows where you are, and considering how often you use the zones in comparison to how much you don't, it's easy to see how they just aren't worth the effort in controlling them.
It's a binary problem. You either own the zones you need, or you don't. You are either strong, or weak. Therefore, it's an easy choice for the enemy. Make him weak, easy team fight, easy game.
People dislike the capturing mini game. That's fair enough, I don't like it either. It shouldn't feel like a stitched on piece of his kit, it should feel integrated. It's an interesting foray into introducing new objectives, but I don't see it working. At least, not without radical changes, changes which Skarner doesn't need.
I've quickly thrown together a few changes to make.
Option 1: Make the zones easier for Skarner to capture.
Always provide the movement speed, regardless of the zone owner. Allow Skarner to instantly capture them, no matter what. This way, it feels more a part of Skarner's kit, instead of another objective. It always would benefit Skarner and - if exploited correctly - differentiates the good Skarner players from the bad ones. Good ones may play around the edges of these zones, baiting around the threshold.
If it's easier for Skarner to capture the altars, then enemy team should find another way. Target the scorpion, push another lane, CC Skarner and focus the back line.
Option 2: Make the altars a decision for the enemy.
Is it worth taking the zone? We could take it, but that might [blank]. There needs to be a decision made, and I believe it should always be "Yes" for Skarner. However, that doesn't always have to "Yes" for the other team. If the altar dealt significant damage to those capturing it, they may think twice about capturing it. Let's pretend that it does, for a moment.
Team A are preparing for a Baron fight. Team B have Skarner, and are approaching. The Baron altar is owned by Team B. Obviously, 1 Team A tank should capture it, because they would take less damage. But what if Skarner kidnaps them in time? They might die, and it would be a 4 v 5. If they don't capture the altar though, Team A could surprise Team B from a bush, and win the fight.
See? The altars shouldn't always be a "Yes" for the enemy team.
Option 3: Change it to some extent.
Example 1) Let Skarner place the altars down at the beginning. They could run out after a duration, then he could replace them. Example 2) Taking damage increases speed and causes walls to form behind Skarner temporarily. Allies can pass through. Example 3) Successive spell hits on targets give Skarner gives attack and movement speed. Synergises with his Q
Note: Option 1 and 2 could work together.