Greatshields in Elden Ring Nightreign are massive shields with high protection, but a small parry window. They are perfect for tanky builds, especially if paired with weapons that allow attacking while guarding. They excel at blocking powerful attacks.
NightreignGreatshields - Nightreign Wiki

Ant's Skull Plate
Greatshield • Lvl Required 1
Weapon Skill: Shield Bash
Brace behind shield before using bodyweight to ram foes while maintaining guarding stance. Weaker enemies will be shoved backwards, and can even be staggered.
Huge head of one of the giant ants which inhabit the two underground rivers, used without modification as a shield. Excels at repeling enemy attacks. Giant ants are venomous creatures.

Briar Greatshield
Greatshield • Lvl Required 1
Weapon Skill: Shield Bash
Brace behind shield before using bodyweight to ram foes while maintaining guarding stance. Weaker enemies will be shoved backwards, and can even be staggered.
Greatshield from a foreign land, used by Elemer of the Briar. Attacks with this armament utilize the iron thorns that have been wound around its frame. Originates from Eochaid, a land of proudly solitary ascetics.

Crossed-tree Towershield
Greatshield • Lvl Required 1
Weapon Skill: Shield Bash
Brace behind shield before using bodyweight to ram foes while maintaining guarding stance. Weaker enemies will be shoved backwards, and can even be staggered.
An iron greatshield large enough to cover the entire body. Emblazoned with an old, interleaving tree. Greatshields boast high damage negation and guard capacity, making enemy attacks easy to repel.

Crucible Hornshield
Greatshield • Lvl Required 1
Weapon Skill: Shield Bash
Brace behind shield before using bodyweight to ram foes while maintaining guarding stance. Weaker enemies will be shoved backwards, and can even be staggered.
Greatshield of red-tinged gold carried by Crucible Knights. Features a great horn. An ancient holiness dwells within. The crucible horn skewers foes when performing shield bashes.

Cuckoo Greatshield
Greatshield • Lvl Required 1
Metal Greatshield painted with a peering cuckoo. Carried by the enchanted knights sworn to the academy. Boasting high magic damage negation, this shield is used to hunt down mages. “Our enemy is none other than Caria itself.”

Distinguished Greatshield
Greatshield • Lvl Required 1
Greatshield featuring sumptuous ornamentation used by the scions of great families. Due to their excessive size, these shields were at times seen as the hallmark of little lordlings who were too timid to earn a few nicks and scratches.

Dragonclaw Shield
Greatshield • Lvl Required 1
Weapon Skill: Shield Bash
Brace behind shield before using bodyweight to ram foes while maintaining guarding stance. Weaker enemies will be shoved backwards, and can even be staggered.
Greatshield said to have been whittled from the claw of a great, ancient dragon, wielded by grotesque Tree Sentinels who yet serve the Erdtree. Imbued with lightning.

Dragon Towershield
Greatshield • Lvl Required 1
Weapon Skill: Shield Bash
Brace behind shield before using bodyweight to ram foes while maintaining guarding stance. Weaker enemies will be shoved backwards, and can even be staggered.
Tower shield engraved with a dragon, symbol of protection. Heavy even among greatshields, it possesses exceptional guarding ability The ancient dragons, who ruled in the prehistoric era before the Erdtree, would protect their lord as a wall of living rock.

Eclipse Crest Greatshield
Greatshield • Lvl Required 1
Metal greatshield painted with a sun in eclipse. Carried by the headless mausoleum knights. The eclipsed sun, drained of color, is the protective star of soulless demigods. It aids the mausoleum knights by keeping Destined Death at bay.

Erdtree Greatshield
Greatshield • Lvl Required 1
Weapon Skill: Golden Retaliation
Ready the shield to unleash its protective incantation. This will dispel sorceries and incantations, retaliating with golden power.
Weighty greatshield forged of gold carried by the order of Tree Sentinels, heavily equipped knights. Blessed by an old incantation of protection. The living rampart of the Erdtree, the Tree Sentinels are the standard to which all defenders of the Erdtree aspire.

Fingerprint Stone Shield
Greatshield • Lvl Required 1
Weapon Skill: Shield Bash
Brace behind shield before using bodyweight to ram foes while maintaining guarding stance. Weaker enemies will be shoved backwards, and can even be staggered.
A great stone shield with an intricately carved fingerprint design. One of the heaviest of all greatshields. Part of the tomb of an ancient god, the Readerless Fingers relayed their message through these imprints, said to be the very seeds from which frenzy first sprouted.

Gilded Greatshield
Greatshield • Lvl Required 1
Metal greatshield coated with gold. Carried by knights loyal to Godrick. The red tinge in the gold coat mirrors the primordial matter that became the Erdtree. The color of homeward yearning.