Astralith is widely considered a low tier legendary in need of a buff. In the Dark Elves faction there are a lot of higher value Epics than Astralith.
She brings a strong Aura for the Arena but her abilities are far too situational to really bring any consistent value. She can kill anyone with her bombs if built with high speed and high attack!
She does not need any Accuracy in her build therefore you can push a more offensive build.
The best combination for Astralith is to pair her with a champion who can make her unkillable and then utilise her A3 to switch health with an enemy.