Stronger Fire Boss

Removed existing features due to conflicts with the newly introduced Unchained Combat or because they were too OP.

New features:

1. Fireboss's damage cap in Soul Mode reduced from 25 to 10; overflow damage reduction percentage remains unchanged but is now configurable.
2. Fireboss gains 1 second of invincibility after taking damage in Soul Mode and regenerates 1 HP per second; this enhancement is disabled by default and configurable. 
3. The weapon wielded by Fireboss now defaults to having Sharpness V enchantment.
4. Fireboss's Flame Dagger-related attacks now additionally apply a stacking Rend effect.
5. Duration of negative status effects on Fireboss in Soul Mode reduced by 50%.
6. Fireboss's armor toughness in Soul Mode increased by 5 points; this enhancement is disabled by default and configurable.