Generic info:
This wacky gobbo is a D&D character, so a lot of her is based on abilities from that game. In the game she is a Barbarian, which means she can get real mad.

My gobbo has powers from the depths. Think of mysterious creatures like krakens and bioluminescent fish-kind, because that is what I based it on.

That is why, when she gets angry (rage), she can sprout tentacles to attack her enemies with. One tentacle forms a tail (as seen in reference 1), which is a tentacle with some sort of tentacular club, and two regular tentacles serving as extra arms (think of it as the Pokémon Machamp, except two arms are tentacles).

However, when she is not angry, none of those tentacles are there, and she just looks like an aquan-inspired goblin, having some fins, webbed fingers, and her bioluminescence does show up in the dark. To see which parts are bioluminescent I would refer to reference 1 as well.

References:
1. as drawn by an artist
2. my initial sketch

What I want:
That is actually open; I would love to see her rage with all her tentacles active, but having her just be a commoner walking about also seems very fun. I would expect her to wield either a greatsword or a two-handed axe in combat.

So the options are.
1. Showing her during a rage; one (clubbed) tentacle serving as a tail, two regular tentacles as extra arms, optionally wielding a two-handed weapon which she would wield with her actual hands.
2. Casual piece; no tentacles anywhere. She is an adventurer, so she visits taverns, fights monsters (without the rage), she has friends to vibe with, she swims, loves to eat (mostly carnivorous)... there is a lot of freedom in this one
3. Any of the above, except underwater.
4. A reference sheet; no dynamic poses or whatsoever, just a front/back, normal/rage, bioluminescence... if you want to make it elaborate you can design her a dedicated weapon if you enjoy creativity.

And even then I am open to anything else you can come up with.

(if you really want to read up on what type of Barbarian this girl is to understand the skillset better, here is a link to Barbarian: Path of the Depths)

Disclaimer: Please understand that, yeah I know anime exists, but all this tentacle business is meant for 100% combat purposes, please do not try to make anything spicy out of this, I will not appreciate it. I want her tentacles to be brutal, not for ... weird pleasures. Thank you.