Multiclassing isn’t built into the Blue Lotus Hack as-is, but all things being equal I don’t see any reason not to have it on the table as an option. The more variety the merrier, says I, and this is one way to handle it.
Something maybe like this:
- first and foremost: since there is no XP, when you gain a level you just decide which class you’re adding the level to
- but remember, this is a 10-level system and you will lose options quickly; you will never “max out” a class if you multiclass
- when you first take a level in a new class you gain:
- hit points according to a roll of that class’s Hit Die
- access to that class’s weapon and armour permissions
- the attack damage of that class, if better than your initial class
- the basic abilities of the class
- choose which class you’re gaining a level in whenever the opportunity comes up; you do not need to abandon your initial class (unless this is a game houserule)
- you do not get to stack hp rolls, or bonuses to attribute checks when leveling up
- use whatever Hit Die or check bonus is appropriate to the gained you just leveled
- only non-caster levels count towards gaining a new ability; only caster levels count towards gaining new gift/spell slots
- if a level is lost due to level drain or similar, start with the most recently gained class; if you can’t remember the order after that, alternate them
- or: drop the highest class level until they match, then alternate