@Tetrahedron  
Hmm, yeah. Sounds about right.

@Communist Starlight  
I actually rebeat Thunderhead again for like the fourth time. Now I have the perfect strategy down that I never fail with at all.
 
Use Magic Beam II to take out all the Turrets but don’t do much damage to Thunderhead yet. When almost all or all of the destructible ones are taken out, then you can start whittling down Thunderheads HP, but whenever a Combat Drone spawns, you must stop attacking Thunderhead and deal with it with Magic Beam II. When it is destroyed, you can continue damaging Thunderhead, until the next Combat Drone spawns, and so on. It takes considerably longer and makes the battle drag on, but it is the safest and best strategy.

@Tetrahedron  
I did it with no healing potions, I thought I couldn’t use them :/

You think those were hard? Try battling Thunderhead, while underleveled, maining spells, and only having 30 regular/small heal potions. I died so many times, but eventually beat Thunderhead finally. The trick for me was to use Magic Beam II to take out almost all of the turrets, and then use Black Sun II to start attacking Thunderhead. The orb things that come in when Thunderheads HP starts going down near the middle are very dangerous when there are lots of them near the end of the battle. You MUST teleport away from them or the massive contact damage will make you take even more damage, and at this point, you are probably taking so much damage that you can’t afford to regen health anymore (besides potions). At that point, its a matter of whittling Thunderheads HP down with Black Sun II and take it out before you are the one who gets taken out.
 
The Zebra boss, Mchavi/Necromancer was the boss that gave me the most hell, but eventually I beat her. Magical Shield + Distortion Field + Moonblade = OP. Just make sure you have lots of potions to heal with, lots of magic potions, especially lots of potions of purifying. Thunderhead though is hard for different reasons, one being obviously that it is the final boss, but two being that it is a really intense and difficult bullet hell.

@Background Pony #1E4F  
That boss made me.lose a few years of my life.  
Until recent ly, I couldn’t defeat this now without dying several times over…

@Communist Starlight  
Why? She is kind of hard, but it’s a climatic, dynamic fight where you have to use most of your wits to defeat her.
 
The necromancer zebra was way worse.

God f***ing damnit, I HATE this boss!