Reinforce has been removed from the mod in the traditional sense.

Now, passive base damage is added after defeating the following bosses:

• Abyss Watchers
• Yhorm the Giant
• Aldrich, Devourer of Gods
• Twin Princes
• Sister Friede
• Halflight, Spear of the Church

These bosses drop new key items that provide the modifier:

• Shattered Sword: from the Abyss Watchers
• Heart of a Giant: from the Yhorm the Giant
• Accursed Skull: from the Aldrich, Devourer of Gods
• Prince's Finger: from the Twin Princes
• Frigid Diadem: from the Sister Friede
• Trespasser's Eye: from the Halflight, Spear of the Church

These key items provide the following modifiers:

• Shattered Sword: grants 10% attack power to all weaponry.
• Heart of a Giant: grants 15% attack power to all weaponry.
• Accursed Skull: grants 20% attack power to all weaponry.
• Prince's Finger: grants 25% attack power to all weaponry.
• Frigid Diadem: grants 25% attack power to all weaponry.
• Trespasser's Eye: grants 25% attack power to all weaponry.