I only died because it scared the shit outta me because it spawned underground and then freakin jump teleported to me and then one of those ghost hands screwed me over
There isn't an easy way to cheese EoL.
You could try attacking her at long distance and dodge her projectile hell with Shield of Cthulhu or Master Ninja Gear, but just like Moonlord she can easily catch up to the player due to her speed.
If you shoot 1000 flares then that's the projectile cap and then she can't shoot projectiles and those are her primary attack so you can just fight her. Without projectiles of course...