Sometimes the initial idea proves to be useless at best. As with this guy:
Soooooo, he meant to be a slow moving tank. Time proved that in my game, there is simply no place for such slow enemies. They simply pose no threat whatsoever, because they are so easy to outmaneuver.
I needed to make him something else, so I changed him to something closer to a support. He is still slow and tough, but now he speeds up enemies in his proximity and spawn some smaller guys, while he is no longer capable of attacking directly. But let's face it - does he look like he can somehow attack directly? Cooldown for spawn seems a little long now, but I feel that it's better to make it to long now, than making the game impossible by making these guys swarm the map with their spawns. Will see how it will unfold and make it shorter if neccesary.