Tentacles appeared in Defiance. They were encountered by both Kain and Raziel, but Raziel fought them the most. We first saw them in the Cemetery, shortly before Raziel found the game's only Planar Portal. Notably, Tentacles assisted the spectre of the original, Vampire Nature Guardian (one of the Ancients) in its battle against Raziel. They were active in both the Spectral Realm, and the Material Realm.
Despite appearances, the Tentacles were not appendages of the Elder God. They were independent creatures, although they may have been related to the Elder in some way. According to Prima's Official Defiance Strategy Guide, the Tentacles were cross-planar beings that were native to the Spectral Realm. They could enter Nosgoth's Materal Realm due to the weakening of the dimensional boundaries, caused by the the decline of the Pillars.
The Tentacles' method of attack was to hide underground until Kain or Raziel approached. Once they detected Kain or Raziel's presence, the Tentacles would emerge suddenly and try to grab them. If the surprise assault was successful, a Tentacle would wrap around Kain or Raziel tightly, slowly draining their energy while they were vulnerable and trapped. In Raziel's case - if he was in the Material Realm - the Tentacles could pull him into the Spectral Realm with them if he didn't escape their grasp quickly enough. Kain and Raziel could break free from the Tentacles' grip by attempting to attack repeatedly.
If a Tentacle's first attack missed, they could still take a swipe at Kain or Raziel with their three-clawed 'hand'. Also, they could burrow underground and have another go at surprising Kain or Raziel in a different location. The ground would appear cracked where a Tentacle was burrowing below. Kain and Raziel could kill the Tentacles by severing them with the Reaver when they surfaced.
The Tentacles were seen to have red blood when they were severed (in contrast to the Elder God's green blood). However, Kain could not feed from them, nor did they release souls for Raziel to devour. They might have been souless creatures, but it's not conclusive; demons in Defiance didn't release souls either, despite having them in Soul Reaver 2.
- Defiance: Prima's Official Strategy Guide (ISBN 0761544674)
- The Defiance Game Manual (UK and US versions)