Boon of Multiclassing (5e Epic Boon)
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Boon of Multiclassing
Prerequisite: Must meet the multiclassing prerequisites of the chosen class.
Choose a class in which you have less than 20 levels. You must meet the multiclassing prerequisites of the class you select. You gain a level in the selected class according to the multiclassing rules, with some exceptions:
You do not gain any more Hit Dice. However, if the Hit Dice of the new class is higher than any of your existing Hit Dice, you may upgrade one of your Hit Dice to the new class’s Hit Dice. You also gain hit points equal to half of the class’s Hit Die size minus three (minimum 0). Your Constitution modifier does not apply to this.
No ability can progress beyond 20th level using this boon, even with abilities that are cumulative among classes, such as spellcasting and proficiency bonus.