Banner
Every 50th kill of this enemy drops Evolution Beast Banner.where it comes from
It has no spawn of its own. Kill the Lunatic Cultist, the pillars land, and this one belongs to the Nebula Pillar. It appears inside that pillar's zone for as long as the shield is up, and nowhere else in the world.
two attacks, one problem
The charge is what kills people. It closes fast and lands like the unicorns and wolves it borrows its movement from, and at the pillar you are already juggling three other things. The sphere it throws does home in on you, but it travels slowly enough that any reasonable set of wings leaves it behind.
Knockback answers both. Anything that pushes it back denies the charge outright, and once it cannot connect it is just another body between you and the shield count. Staying airborne works for the same reason.