Hybrid TB is what I enjoy playing against Minion Erebus.
Blade of the Serpent-Cold Aura-Rain of Ice will meet all your mana needs so you're free to stack up armor and speed for all of your slots.
Stay safe early game and farm creeps constantly due to your neverending mana and as the game progresses just prioritize points in RoI and Cold Aura and the two extra in Ring of Fire. You can help protect the towers and keep Minion LE honest for a while with your area affect and mass killing of enemy creeps so he has less bodies around to make new nightwalkers. Once you get to level 9 get Frost Nova and he's essentially neutered: RoF (depending on the situation, otherwise just approach in cold mode), then Frost Nova, then drop RoI and hit BlotS before it hits filling up your mana completely, switch forms to fire, etc etc...
1-RoF (better for the start of the game brawl at the XP flag)
2-RoI (you can now tag all creeps behind the tower
3-Cold Aura (you're now harder to chase down and kill)
4-RoI II(you are now a neverending mana, creep farming machine)
5-Cold Aura II (you haven't armored up yet so you need to be able to get away)
6-RoF (only use your fire ring when you feel completely safe)
7-RoI III (you're now a priest farmer, yay!)
8- Cold Aura III (-10% speed for them so if you got boots of speed you can outrun some builds... bout half I think?)
9- Frost Nova (use it only when you have to to save yourself or a buddy, or are about to recharge your mana with Blade/Rain)
10- RoI IV
11- Frost Nova II
12- RoF III
13- RoF IV
14- Save
15- Frost Nova III and Insp Flame <-- best level 15 skill in the game IMO
Works for me against tower rooks and minion builds, but I don't play in top level games much.