The Grim Temple is the final level of The Ruins in The Legend of Zelda: Tri Force Heroes. Prismantus is fought here. The Grim Temple is a large, dark crypt filled with the undead and ghosts. The Level features the colored platforms present in Illusory Mansion, as well as the vanishing purple platforms that appeared in the Lone Labyrinth. Because of the temple's perpetual darkness in certain chambers, the Light Armor becomes useful here.

Stage 1

In Stage 1, the Links begin at the corner of a pitch dark chamber. Ahead of them are a Boomerang, a Gripshot and Fire Gloves. Immediately after the items are taken, monsters spawn in the darkness, including Rats and Stalfos. A torch in the center of the room can be lit with the Fire Gloves to help light the room a little. While fighting the enemies, the Links must also be careful of hidden pits in the floor that curve around the room. After all enemies are defeated, the doors to the Triforce Gateway opens, and wall torches light up to reveal its location.

Stage 2

In Stage 2, the Links appear on separate ledges over a bottomless pit. Colored Poes fly nearby, and purple platforms that appear and disappear bridge across the gaps. After the colored Poes are defeated, white Poes appear in their place floating at higher elevations. The Links will have to form a Totem to defeat them. Once these Poes are defeated, a solid purple bridge appears to a platform with a Switch. Hitting this Switch creates another bridge to ledge with dormant Gibdos. Once all three Links are across, the Gibdos will reanimate and must be defeated. A platform of vanishing tiles will also appear to expand the battlefield. The Links must cross this to another ledge, where two more Gibdos are found. After they are all defeated, a bridge appears to the Triforce Gateway.

Stage 3

In Stage 3, the Links appear on a ledge next to some colored platforms. The Links must throw each other across to their respective platforms to reach the next ledge, as well as use their Boomerang or Gripshot. Once they are reunited, a pair of Prankster Poes and Chasupas appear and must be fought. After they are defeated, a pair of ReDeads appear at another ledge to the east, and must be reached using a series of moving, colored platforms. A Squiddy will also appear on the ledge the Poes and Chasupas were fought on. The moving platforms will circle around the ledge the ReDeads are on, however a cannon blasting flames to the right side will burn the Links off of their platforms if they do not disembark on time. Once the ReDeads are defeated, the nearby Triforce Gateway activates, reachable by using the moving platforms.

Stage 4

Stage 4 is where Prismantus is fought in a very dark chamber. Skulls and grass prior to the arena can be cut down for Hearts.