The Warlock can choose any spell he currently knows to cast at the level of Mystic Arcanum that he currently possesses (e.g. Cloud of Daggers, using his 6th level Mystic Arcanum.)
Does Mystic Arcanum count against warlock spells known?
No, the warlock’s Pact Magic feature is a completely separate feature from the Mystic Arcanum feature, and each independently describes how you get spells without relying on or referring to the other. Pact Magic says you get another spell known at e.g. 11th level, so you do, period.
Can you cast Mystic Arcanum with a spell slot?
Mystic Arcanum literally says: You can cast your arcanum spell once without expending a spell slot. You must finish a long rest before you can do so again.
Can you swap out Mystic Arcanum?
No. It’s because it isn’t actually a spell slot, it’s a class feature that only lets you use the selected appropriate level warlock spell.
Do you need components for Mystic Arcanum?
You can cast your arcanum spell once without expending a spell slot. You must finish a long rest before you can do so again. It says nothing about having or needing the material components for the Mystic Arcanum spells. This becomes very important for spells such as Forcecage or Plane Shift.
Can warlocks cast 9th level spells?
Though Warlocks only have spell slot up to 5th level, they have the ability to learn up to 9th level spells using their feature Mystic Arcanum. It’s separate from your spells known, and you can use it once per long rest without expending a spell slot.
Can you Upcast as a warlock?
Yes, the upcasting is actually mandatory. A member of another class can choose to upcast it or not, but Warlocks don’t have spell slots of multiple levels, so as soon as you level up, you’ll start being forced to upcast it, like with any other Warlock spell.
Can Warlocks Upcast spells?
Warlocks get Mystic Arcanum, not spell slots, for levels 6-9. By rule, then, can’t upcast for stronger creatures.
Can you cast Mystic Arcanum at higher level?
Unfortunately, mystic arcanum does not allow picking a lower level spell and upcasting it. The spellcasting rules in the PHB state that when a spell is upcast at a higher level, it’s treated as a spell of that level.
Can you cast Mystic Arcanum more than once?
You can only cast them once per day without using a spell slot. You cannot upcast them. When you choose your 6th level mystic arcanum, you have to pick a 6th level spell from the warlock spell list.
Can a warlock know more than one mystic Arcanum spell?
A spell you choose must be of a level no higher than what’s shown in the table’s Slot Level column for your level. The Slot Level column never increases above “5th”, so a warlock can never know a warlock spell of 6th level or higher. Therefore the Mystic Arcanum spells must be known separately from the warlock’s Pact Magic spells.
When do you regain your mystic Arcanum in raw?
That Mystic Arcanum usage could only be regained upon long rests, a la RAW. The Warlock would still only choose one spell per Mystic Arcanum that they learned. The Warlock would also be able to ‘upcast’ his lower level Mystic Arcanums, should they allow it (e.g. Create Undead, at level 9).
Where do you find spells known in Warlock?
The Spells Known column of the Warlock table shows when you learn more warlock spells of your choice of 1st level and higher. A spell you choose must be of a level no higher than what’s shown in the table’s Slot Level column for your level.
Is the Mystic Arcanum the same as Pact magic?
If that reasoning is not convincing, here’s a bit of circumstantial evidence underlining the necessary separation of the two features: Notice that the spells you gain access to with Pact Magic and Mystic Arcanum cannot be the same due to incompatible spell levels!
