This game is balance more than you think
Take a look at the stats of each demigod rank:
http://pantheon.demigodthegame.com/demigods/
Now I seen the top 4 rotate position around a few times these 3 weeks. It looks like there isn't any Demigod that is overpowered. The only underpowered Demigod is Queen of Thorn.
Rook's tower is not over OP
Regulus mines and snipe is not OP
Erebus bite is not OP
Unclean beast damage is not OP
It only feels like they are OP because you died to them 2-3 games in a row and you don't know how to beat them.
When it's 1v1, I can see that some are stronger (like rock, paper, scissor). But in a team 3v3 or 5v5 game, you can pick any combination of the 8 demigod and you have a chance of winning. If any of them are OP, you would see winning percentage of 60% or higher.