In Fargo's Eternity Mode, regular Skeletron has a brief Dungeon Guardian phase with 50 HP, where you're supposed to basically hit it fifty times with random 1dmg attacks.

However, Draedon update introduced this:

If the player does less than 1 damage to a boss, the damage is no longer rounded up to 1 (2 on a critical hit) and is instead rounded down to 0.

Which makes this gimmick phase impossible unless you can deal 5000 dmg per hit (to counteract the 9999 armour), which is obviously not possible at this stage of the game.

Any way to overcome this? I'll probably just disable Eternity Mode for this boss and come back to it later, so it's not really a huge deal.