[DK rework idea] Simple change for berserk

Hello, as we all know the crux of DK gameplay in GMS was to keep your health below half. This minigame worked out well before people started to catch on to washing, as monsters didn't do that much dmg.

Currently, the issue is that DKs struggle in endgame content, where monsters hit too hard to maintain zerk effectively. Adding a smoother damage curve mitigates this slightly, but still leaves DKs unable to access their normal dpm. Additionally, warriors are already pot guzzlers, and DKs that lack power guard/guardian and survive on a diet of sushi and ice cream are even more expensive to upkeep.

My proposal tries to keep the spirit of the original DK skill, while keeping it relevant for modern damage numbers and pot optimization.

Proposal
* Revert berserk back to a flat 2x multiplier (or keep 2.2, either way make it flat)
* Get rid of active zerk as it isn't needed (or change it to give invincibility/stance/something else)
* When berserk is active, i.e. hp is below half, apply a 50% damage reduction.
* [optional] Berserk does not apply while under sed, to address broken luk dk concerns

Pros
* Preserves the original spirit of the berserk skill
* Thematically consistent, as the state of being "berserk" i.e. having adrenaline is associated with being able to shrug off injuries
* Allows skill to be rewarded - harder to keep under 15k than to mash power elixirs. With this rework, both dmg and survivability are tied to hp - potting up to 16k can mean death. (side note, I personally don't mind dks doing middling damage. this rework idea just makes dks able to achieve full dpm at endgame bosses)
* Gives zerking dks the same survivability as other warriors, minus shield/guardian
* Addresses pot cost concerns for dks. It's worth eating sushi when they effectively do the job of ginseng roots. Sushi and ice cream pops are never overpowered because of the prevalence of roots, elixirs, ales, pe.

Possible concerns
* Gives full health lazy dks/mules a bit more survivability (can tank 2 19k hits instead of 1)
* Makes ginseng roots really good, in some situation on par with ales. But warriors pay more in pot costs anyway so it doesn't feel broken
* Buffs dks

Discuss