Multiclassing comes with its own set of rules regarding Spellcasting though, which Shapechange fail to address, things such as spell slots etc..
Shapechange does not fail to address them, creatures simply don't use spell slots, thus when you cast a spell from the creature's stat block, it does not use spell slots but if you used your own spellcasting feature while in shape change, that does use spell slots.
Concentration is also easily resolved, if you attempted to cast a spell that needs concentration then shapechange itself would end and so realistically the list of usable spells is slightly reduced. If you changed into a Dryad as an earlier example, you can not cast pass without trace or Entangle since they are both concentration spells and Shapechange is a concentration spell.
@R3sistance The Shapechange spell doesn't address what happen if the monster has Spellcasting, only saying you retain yours. But statistics you retained shouldn't be duplicated but have only one INT, WIS, CHA for example.
But i think i remember why i originally answer in another thread that they would both work, Monster Spellcasting isn't a feature or trait anymore as Thezzaruz said, its an Action.
Going back full circle to my original position i think you'd get both ;)
Multiclassing comes with its own set of rules regarding Spellcasting though, which Shapechange fail to address, things such as spell slots etc..
Shapechange does not fail to address them, creatures simply don't use spell slots, thus when you cast a spell from the creature's stat block, it does not use spell slots but if you used your own spellcasting feature while in shape change, that does use spell slots.
That's why, IMO, if you use Counterspell successfully against a monster, the spell cast by that monster is lost and the number of uses isn't recovered.
Limited Usage
Some parts of a stat block have restrictions on the number of times they can be used. Here are the most common ways that usage is limited:
X/Day. This notation means the stat block part can be used a certain number of times (represented by X) and that a monster must finish a Long Rest to regain expended uses. For example, a Reaction that includes “1/Day” means the Reaction can be taken once and that the monster must finish a Long Rest to take it again.
Concentration is also easily resolved, if you attempted to cast a spell that needs concentration then shapechange itself would end and so realistically the list of usable spells is slightly reduced. If you changed into a Dryad as an earlier example, you can not cast pass without trace or Entangle since they are both concentration spells and Shapechange is a concentration spell.
Shapechange does not fail to address them, creatures simply don't use spell slots, thus when you cast a spell from the creature's stat block, it does not use spell slots but if you used your own spellcasting feature while in shape change, that does use spell slots.
Concentration is also easily resolved, if you attempted to cast a spell that needs concentration then shapechange itself would end and so realistically the list of usable spells is slightly reduced. If you changed into a Dryad as an earlier example, you can not cast pass without trace or Entangle since they are both concentration spells and Shapechange is a concentration spell.
Monsters don't have a spellcasting feature though, they have actions that sometimes produces a spell. I don't see where the problem lies tbh?
@R3sistance The Shapechange spell doesn't address what happen if the monster has Spellcasting, only saying you retain yours. But statistics you retained shouldn't be duplicated but have only one INT, WIS, CHA for example.
But i think i remember why i originally answer in another thread that they would both work, Monster Spellcasting isn't a feature or trait anymore as Thezzaruz said, its an Action.
Going back full circle to my original position i think you'd get both ;)
That's why, IMO, if you use Counterspell successfully against a monster, the spell cast by that monster is lost and the number of uses isn't recovered.
Good observation.