My Big Bad: The Elder Thing (an aboleth)

[Nonah_Me]

Hey folks, I'd like a little advice. How could I incorporate spellcasting into the aboleth, in order to make it a threat against level 15 player characters? I'm thinking illusion magic, because of the ability aboleths have to project stuff into the minds of victims, etc.

Would giving it wizard spellcasting work? Or just a spell list that it can use x/per day?

I do plan on there being minions, but this is the climactic encounter of the entire island the PCs find themselves on, and it relates to one of the character's backstories, so I'm hoping it's memorable.

Thanks!

[Belac93]

I would say give it some levels as a Mystic. (http://media.wizards.com/2016/downloads/Psionics_and_Mystic_V2.pdf) Seems like it would fit.

[krugaan]

Most of my 2E career was spent playing a great campaign called the Night Below, where (spoiler alert) the BBEG was a singular aboleth avatar who was trying to dominate the world.

Mechanically, tons of hitpoints, bunch of spells, minions, and acid blood.

[INDYSTAR188]

When it comes to DMing I always think, mechanically, the simplest option is generally the best. So I would just pick the spells you think are appropriate.