In D&D 5e's Warlock flavor, it would make sense that incredibly powerful (i.e. > level 20) spellcasters could become the patrons. So, in preparation for a new campaign (with my DM's permission), I am creating a new Magister warlock subclass. It essentially hinges on my Warlock being taught in some way by a more powerful caster.
Before I play this campaign (and possibly future campaigns, if it proves balanced), I would like to see how balanced this is, so as to avoid having to change the features throughout the campaign.
Here it is:
You have made a pact with the spirit of an exceptionally powerful mage who draws from unfathmable vestiges of magical power, and you have gained further arcane knowledge through their tutorship.
Magister's Spell List
When you choose this path at first level, you may choose the type of spellcaster you are learning from. The spells on the corresponding spell list count as Warlock spells for you, and you always have them known.
1st Level: Magic Missile
2nd Level: Blur
3rd Level: Major Image
4th Level: Greater Invisibility
5th Level: Wall of Force
1st Level: Chaos Bolt
2nd Level: Aganazzar's Scorcher
3rd Level: Haste
4th Level: Banishment
5th Level: Cloudkill
1st Level: Hex
2nd Level: Invisibility
3rd Level: Hunger of Hadar
4th Level: Shadow of Moil
5th Level: Synaptic Static
Okay. This is a pretty big deviation from the typical "expanded spell list," but if you think about it, the flavor works. This patron has taught you these spells from its own experience, not just granted you the chance to learn them.
Lesser Mystic Arcanum
At 1st level, the Magister has taught you a magical secret called an arcanum. Choose a 1st-level spell from the Warlock spell list as this arcanum.
You can cast your arcanum spell once at its lowest level without expending a spell slot. You must finish a long rest before you can do so again.
At higher levels, you gain more warlock spells of your choice that can be cast in this way: one 2nd-level spell at 3rd level, one 3rd-level spell at 5th level, one 4th-level spell at 7th level, and one 5th-level spell at 9th level.
This is the defining feature of this subclass. Usually, Warlocks begin getting Mystic Arcanums at 11th level, to offset their lack of spell slots, but this feature grants you a few low-level ones at the lower levels (1-5). This gives this Warlock a bit of a safety net of one-time-use spells.
At 6th level, when you cast a Warlock spell, you may use a bonus action to Dash or Disengage.
This gives the average Warlock some ways to escape combat easily, but then again, what self-respecting (non-Hexblade) Warlock would find themselves in melee? Dash, however, is a very practical option, and may be too overpowered. Should I only allow the Disengage option? Or perhaps I should include Dodge instead?
At 10th level, you can use your action to weave a web of magic around yourself. For 1 minute, you gain temporary HP equal to twice your Warlock level, and your concentration cannot be broken until you lose all of these temporary hit points. Once you use this feature, you cannot use it again until you complete a short or long rest.
Some potent defensive magic, much like other Warlock features at 10th level.
Greater Mystic Arcanum
At 14th level, you gain the ability cast your 1st-level Mystic Arcanum at-will. At 18th level, you may cast your 2nd-level Mystic Arcanum at-will.
The capstone ability for this subclass stacks at 18th level, and allows you to cast (probably utility) spells at-will, from a very limited (cough) Warlock Spell List (cough) list of options. Additionally, it hinges on an ability you selected a LONG time ago, back at first and third levels.
Is this homebrew warlock patron balanced against the other Otherworldly Patrons?