The original post featuring The Great Mother was intended as a truly epic threat to PCs – every bit as tough to fight as Tiamat and other CR 30 foes. And while I do think she was successful in that, there are other additions I planned but never got around to – namely, Lair Actions suitably scary for a God of Beholderkind, and a sort of “birthing” mechanic for this #1 mom.

The Great Mother’s Lair

When not wandering the planes babbling insanities and gobbling up whatever strikes her fancy, the Great Mother dwells in the 6th layer of the Abyss, known as the Realm of a Million Eyes. This cavern system of innumerable twisting tunnels, many of them vertical and alien in their construction, were studded with eyes linked to the Great Mother herself…always watching.

Evil beholders and beholderkin of every type were abundant within her realm, though none dared delve so deep they encountered her true lair – a massive cavern sub-plane hidden deep underneath the sinkholes and shafts. Within this chamber she would spawn ever more beholders, eating anything that came near, even progeny that stayed too long.

In the Great Mother’s true lair, she loses her Discorporation trait…though any heroes who might defeat her in the heart of her realm to destroy her utterly are advised to bring the strength of an entire pantheon with them.

Lair Actions

While these conditions are truest within her Abyssal realm, the Great Mother can manifest lair actions anywhere she remains for at least a day, owing to the reality-warping powers of a true beholder god. On initiative count 20 (losing ties), she can take one lair action to cause one of the following effects:

• Creeping Protoplasm. A 50-foot square area of ground within 250 feet of her becomes slimy and warped; the area is difficult terrain until initiative count 20 on the next round. If any creature is knocked prone or has their speed reduced to 0 within this area, the slime grows up their body in a thin, sticky layer and beholders (including the Great Mother) never count that creature as unseen. The slime can be removed by washing or scraping it off manually (an action) or exposing it to a full round of sunlight; otherwise it persists even after this lair action ends.
• Warp Tentacles. Walls within 250 feet of the Great Mother and her own body sprout grasping appendages until initiative count 20 on the round after next. Each creature of her choice that starts its turn within 10 feet of a wall or the Great Mother must succeed on a DC 26 Dexterity saving throw or be grappled. The Great Mother may immediately choose to teleport any creature who fails to a location within 50 feet of her, which does not end the grapple.
• Crossfire. Three eyes open on solid surfaces within 120 feet of the Great Mother. One random eye ray (as if fired by a standard Beholder) shoots from each eye at a target of her choice that she can see. The eyes then close and disappear.

The Great Mother can’t repeat an effect until they have all been used, and she can’t use the same effect two rounds in a row.

The Great Mother: Blasphemous Birth (Optional Rule)

If you wish for an even more dramatic fight against the Great Mother, the Vile Birth optional rule creates a Mythic version of her. Reduce her Hit Points to 500, and give her the following Mythic traits:

Eyes of the Mother (Mythic Trait; Recharges after a Short or Long Rest). When the Great Mother is reduced to 0 hit points, she doesn’t die or fall unconscious. Instead, she loses one of her ten eye stalks. The Great Mother then has nine eye stalks in total, each with 60hp and AC 25. They are immune to bludgeoning, piercing, and slashing damage from nonmagical attacks and all conditions. Effects that damage an area used on the Great Mother can only damage one eye stalk at a time. If they are forced to make a saving throw, treat their ability scores as 10 (+0). For each eye stalk destroyed, that result on her Eye Rays trait cannot be used, and she makes a Maw attack instead (eye stalks cannot be attacked by a creature who is swallowed). If she finishes a short or long rest, her eye stalks return. The Great Mother dies when all her eye stalks are destroyed.

Mythic Actions

If the Great Mother’s mythic trait is active, it can use the option below as a legendary action after using Eyes of the Mother.

Blasphemous Birth. One of the Great Mother’s fallen eyes bursts, and her children rises to defend her. Make a d20 roll and consult the following table. The Great Mother can use this legendary action a number of times equal to the number of eyes she has lost (up to nine). Her children appear anywhere within 50 feet of her and roll Initiative as normal.

Roll	Result
1-5	Gauth
6-10	Death Kiss
11-15	Beholder
16-20	Death Tyrant

The Great Mother Tactics

While the Great Mother’s original stat block functioned much like a standard Beholder, just more in every way, including her Lair Actions and/or Mythic traits allows for a bit more strategy, and while the Mother of All Tyrants may be utterly mad, she is not without a kind of nigh-mindless genius in her endless consumption and creation.

• Creeping Protoplasm can be combined with her or other beholders’ eye rays that incapacitate or restrain, to ensure her enemies don’t benefit from a beholder’s greatest weakness, unseen foes.

• Warp Tentacles serves to adjust the battlefield, especially if her enemies are attempting to hide behind walls for total cover. She can grapple them and then teleport powerful melee foes far away and physicall weaker enemies close, the better to consume them with her maw or blast them with impunity.

• Crossfire makes it that much more likely that she is able to combine eye ray effects for devastating results, such as Restraining a foe so they have disadvantage against her Obliteration or Excoriating Rays.

• While the mythic trait Eyes of the Mother means the Great Mother will grow magically weaker as the fight continues, she will also become more ferocious – using Maw attacks multiple times a turn and birthing more allies with Blasphemous Birth. If her enemies are not careful and sever too many of her eye stalks at once without clearing out her existing children, the battlefield could quickly turn against them as they are blasted from all sides by a massive barrage of saving throws.