Mystic Arcanum on the Spellcaster Helper
The RPGist's D&D 5e Spellcaster Helper now supports the warlock Mystic Arcanum class feat.
On the 11th, warlocks characters can learn one 6th level spell.
On the 13th, warlocks characters can learn one 7th level spell.
On the 15th, warlocks characters can learn one 8th level spell.
On the 17th, warlocks characters can learn one 9th level spell.
These spells from Mystic Arcanum do not count on the number of spells warlocks can learn, they can be cast only once per long rest interval each and they do not consume spell slots.