The Black Star is particularly unique, and can easily crush the unprepared.
If you want a primer before entering the Polaric Void, were here to help.
When you load into the Polaric Void, you will immediately notice the center globe.

That globe emits two lines of flame which divide the arena into a fiery-red half and an icy-blue half.
The globe will rotate throughout the fight, shifting the halves with it.
However, they will also take less damage of the opposite jot down.

This is the key to surviving the Black Stars most dangerous attacks.
Note that the pillars around the arena also block attacks but sometimes break.
This is also related to the rotating arena dial and will be important later.

The Black Star has two extremely powerful abilities; Astral Avalanche and Solar Storm.
These attacks will near-instantly kill you if you have their matching debuff.
However, with the opposite debuff, they do far less damage.

See the images below for examples.
Here Im able to tank an Astral Avalanche unscathed by standing in the fire half of the arena.
The fire debuff is stacking up, as indicated by the green arrow.

The same plan works for Solar Storms deadly beams.
Because Im in the cold half of the arena, I take very little damage.
In the more difficult, repeatable version the Black Star fight, things aren’t so simple.
Even with the appropriate debuff, Astral Avalanche and Solar Storm will deal a lot of damage.
You won’t be able to outright tank them without significant regen or increased maximum resists.
If that doesn’t apply to you, you will need to take advantage of the pillars.
Thankfully, you might reduce that too by sticking to the right part of the arena.
Otherwise, one cold attack on the wrong side of the arena will doom you.
Pop it into your map gadget to start the fight.
This first encounter is the story version and is significantly easier than the farmable version youll encounter later.
Completing 14 maps grants access to the harder version of the Black Star.
Thats everything you should probably take on the Black Star in Path Of Exile!