Advice for Building Eldrich Abominations

[Feddlefew]

Here be spoilers for my 5e game, so I'd prefer if my players (the 3 dragon born, 1 orc paladin, and the human Great Old One warlock) stayed out if they've found there way here looking for build advice.














For my campaign I'm cooking up some Great Old One like beings with unique and strange abilities. The intention isn't to make an interesting fight, but instead push home just how strange these beings are, even the young and week ones. What I'm looking for are either extrema versions of existing mechanics, or things that alter core mechanics, like how D20 rolls work. A few ideas I've had:

-Is made up of grey goo (http://tvtropes.org/pmwiki/pmwiki.php/Main/GreyGoo), with all that it entails. Doesn't have shape-shifting, but can condense itself into a solid-ish form when not in combat or crafting.

-All rolls within N feat are done twice, monster chooses whichever result it thinks would be funnier.

-All d20 rolls done within N miles become 3d6 + 2 fudge dice rolls.

-2 or more planes of existence are brought together and temporarily merged in an area of 2.5 miles around monster, at-will, concentration.

[Bhu]

Are these Old Ones awake of asleep? Cthulhu was able to drive psychically sensitive people temporarily mad the entire world over just by stirring in his sleep Granted he's prolly at the upper end of the Old Ones.

[Feddlefew]

All but one are in deep hibernation, deader than dead, or long gone. *Most* aren't hostile, but then again a good proportion of them create conditions not suitable for organic life or don't understand that the creatures of the material world can't self-resurrect.

[Blake Hannon]

Here's an ability I gave to some Old One type critters in an old campaign.

The creature is extradimensional, and moves by reaching parts of itself *around* our plane. Mechanically, the monster has teleportation at will, but whenever it teleports it leaves part of itself behind. As such, the monster exists in two places at once, and can perform actions and make opportunity attacks from both locations. It can even give itself flanking bonuses.

Whenever it uses teleport, one of its "selves" dissapears as it withdraws that appendages and puts it down somewhere else.

[Bhu]

Maybe disrupt the use of telepathic abilities, or you risk mental contact with the Old One briefly.

[Stan]

The creature is extradimensional, and moves by reaching parts of itself *around* our plane.
This is really cool.


How about a sense of confusion and awe? Must succeed at a charisma check to act, new save every round until you come to your senses. It would be somewhat tedious but, if a creature is weird/scary enough, you could require a check every round to for a character to get all their actions (lose bonus actions, only a single action allowed, or something along those lines.)

Suppression of intelligence and/or wisdom by the sheer strangeness. Impairs all skill and spells based on that ability. Could require a concentration (or int or wis) check to get off an affected spell or use an affected skill, with the various entities given a hp damage equivalent.

A creature made of strange magic might have resistance to magic weapons and damage from spells and/or advantage on saves vs. magic.

Totally alien mind gives immunity to all mental based magic, plus caster must make the same save or be stunned.

[Inchoroi]

One thing that might be helpful is to take a look at the RPG Exalted. There's a series of beings called Primoridals, and they all define concepts, either by being that concept, or being everything else of that concept. They each have "excellencies" that define what they can and can't do, so you could use those to define what it is that these sorts of creatures do and cannot do (literally cannot).

For example, one is a river of madness that never stops moving, and cannot speak save to giggle maniacally. Another is an all-encompassing, scathing desert that mandates hypocritical law; yet another is an ocean of acid that gives birth to terrible, mutated creatures.

...ignore mechanics, though. Exalted is insane.