A step beyond Servants, you are a Grand Servant, those summoned by the World to deal with Evils of Humanity gone rampant. The amount of raw power at your disposal is incredible, surpassing even most Divine Beasts, and should you be focused on destruction, your attacks could obliterate islands. You also possess Noble Phantasm which would take properties from the rest of the perks, powers and/or drawbacks you take from this CYOA. The phantasm may boost your power temporarily, reduce the cooldown of abilities, sidestep requirements for ability activation, and so on. The possibilities are endless.
Project V17/Powers/Shardless/Magic and Mystic Power Upgrades/Grand Servant (Type-Moon)
From Worm CYOA Wiki
King of Knights
You have become a living Incarnation of Artoria and Arthur Pendragon, granting you all their memories (of which you may decide if and how they effect you), skills, abilities and blessings, as well as the numerous items and weapons that all the many versions of Artoria and Arthur have ever wielded in the Type-Moon franchise.
Notable examples of such treasures are the Space Armor version of Avalon and her Spaceship Dun Stallion II, wielded by a certain Mysterious Heroine; the Divine Spear & Core held by Goddess Rhongomyniad, who can summon the Knights of the Round Table--with the exception of Galahad and Bedivere--to aid her; and the sword Marmyadose, wielded by her Lostbelt Caster variant, said to exceed Excalibur in power alone.
King of Heroes
You have become a living Incarnation of the world's first Hero, Gilgamesh, granting you all their memories (of which you may decide if and how they effect you), skills, abilities and blessings, as well as the numerous items and weapons that all the many versions of Gilgamesh have ever wielded in the Type-Moon franchise.
Notable examples of such power are the Child-Gil's "the King's Smile," or adult Gil's "A.U.O. Cast Off," able to paralyze even powerful supernatural beings with his raw charisma; Enkidu and his powers, as he considered himself one of Gilgamesh's possessions; and the incredible power he had in CCC, allowing him to directly contradict the will of the Moon Cell, as well as fight on completely equal terms with BB, and later (with some help) destroy Kiara Sessyoin.
King Of Magecraft
You are imbued with the essence of King Solomon, making you a living embodiment of the legendary mage. This bestowed upon you all of the past memories, skills, abilities, and blessings held by Solomon, in addition to a multitude of powerful weapons and artifacts, such as his Clairvoyance of the past and future, The Ten Rings of Solomon, and his immense magical power that would allow you to fight against even the mightiest of foes. You are also able to summon and command the 72 Demon God Pillars, including Goetia. With these newfound powers, you are a formidable force, possessing the power of the great mage, enabling you to take on any challenge with confidence. Your abilities are unparalleled, and no obstacle will stand in your way, for you are a living incarnation of Solomon.
Magus Of Flowers
As a living incarnation of the great mage Merlin, you possess a wealth of knowledge, skills, abilities, and blessings. You have Merlin's memories, which you can choose to access at will, and all his experience. Your skills and abilities are unmatched, and you are capable of doing the extraordinary. In your arsenal, you have his legendary artifacts, including his Clairvoyance, which allows you to see anywhere in the present, and the Garden of Avalon, which you can call upon at your bidding. Not only that, you have access to his incubus bloodline, enabling you to enter the dreams of others and manipulate them to your liking. You are a force to be reckoned with, and nothing can stop you as you wield the power of the legendary mage.
Hero of Charity
You have become the living incarnation of the Hero of Charity Karna This grants you all the memories (how they affect you is for you to decide), skills, abilities/blessings, and numerous items & weapons from various versions of Karna in the Type-Moon Franchise. From Archer, Rider, Santa all the way to Super Karna also kown as Burning Three Gods Karna who weilds the power of Vishnu and Shiva
Greatest Hero of Greece
You have become the living incarnation of Greece's greatest hero, Hercules. This grants you all the memories (how they affect you is for you to decide), skills, abilities/blessings, and numerous items & weapons from various versions of Hercules in the Type-Moon Franchise. These include Archer Hercules' Bow made from the Hydra, his Valor Skill, his corrupted version Alcides' Kings Order twelve-part Noble Phantasm, and Reincarnation Pandora which allows him to absorb the powers and items of his opponents. Additionally, Saber Hercules wields "Marmyadose," a sword stronger than even Excalibur.
Sessho-Seki
You have become a living Incarnation of Tamamo-No-Mae, granting you all their memories (of which you may decide if and how they effect you), skills, abilities, and blessings, as well as the numerous items and weapons that all the many versions of Tamamo have ever wielded in the Type-Moon franchise.
However, this power is dependent on the number of "tails" available to you at any one time. You start with only one tail, equal to Tamamo when she fought inside the Moon Cell, or other single tailed Tamamos such as Tamamo Cat. You will grow more tails over time, dependent on your mastery of the Celestial Brush. The more tails you grow, the more powerful you become, with your final nine-tailed form equaling Amaterasu herself, a being that in raw power alone surpassed even Sefar.
Arhat
You have become a living Incarnation of the Buddhas featured in Type-Moon, granting you all their memories (of which you may decide if and how they effect you), skills, abilities, and blessings, as well as the numerous items and weapons that all the many Buddhas have ever wielded in the Type-Moon franchise.
In particular, this gives you the abilities of Shakyamuni himself, such as granting Moksha to anyone with Amita Amitābha, the abilities of Xuanzang, such as a Buddha Palm strong enough to destroy Divine Spirits in a single strike, & even those of Kiara Sessyoin, for she was a Shingon practitioner who was said to be "similar to a Buddha."
Nameless
You have become a living Incarnation of the various EMIYAs featured in Type-Moon, granting you all their memories (of which you may decide if and how they effect you), skills, abilities, and blessings, as well as the numerous items and weapons that all the many variants of EMIYA have ever wielded in the Type-Moon franchise.
This includes Unlimited Blade Works, EMIYA Alter's Unlimited Lost Works, Murumasa's Tsumukari Muramasa, Kiritsugu's Time Alter, Shirou's mad cooking skills, and Assassin EMIYA's deadly Phantasm Punishment.
King of Conquerors
You have become a living Incarnation of the many variants of Iskandar featured in Type-Moon, granting you all their memories (of which you may decide if and how they effect you), skills, abilities, and blessings, as well as the numerous items and weapons that all the many variants of Iskandar have ever wielded in the Type-Moon franchise.
This includes the vast army of Ionoi Hetairoi, the speed of Gordius Wheel & Bucephalus, the strength of Zeus Funder, the charisma of Rosy-Cheeked Youth & the Charisma skill, and the incredible Tactics that let him refrain from suffering even a single defeat during life.
Hound of Ulster
You have become a living Incarnation of the many variants of Cú Chulainn & Scathach featured in Type-Moon, granting you all their memories (of which you may decide if and how they effect you), skills, abilities, and blessings, as well as the numerous items and weapons that all the many variants of Cú & Scathach have ever wielded in the Type-Moon franchise.
This includes Gaé Bolg, Caster & Skadi's Rune Magecraft including Ochd Deug Odin, Cú Alter's Curruid Coinchenn, Sétanta's Cruaidín Sétanta, Scathach's Gate of Skye, and even Scathach-Skadi's Gate of Aegir if you just want to enjoy a day at the beach.
Gorgon
You have become a living Incarnation of the various Gorgons featured in Type-Moon, granting you all their memories (of which you may decide if and how they effect you), skills, abilities, and blessings, as well as the numerous items and weapons that all the many variants of Medusa & her sisters have ever wielded in the Type-Moon franchise.
This includes Rider's incredible speed & her Pegasus, the Gorgon's many methods to harvest magical energy (like Blood Fort Andromeda & Pandemonium Cetus), Harpe, Chrysaor, Smile of Stheno, Eye of Euryale, & Breaker Gorgon.