The dialogue that was used by the tomb guardian was originally meant for Turel in anoriginal version of Legacy of Kain: Soul Reaver but was adapted to serve for the Tomb Guardian after Turel's removal from the game..
The Tomb Guardian is often known as "Morlock" by fans because during development of Soul Reaver, the vampire brothers were given codenames according to their abilities and Turel's was 'Morlock' (much like the villains in H.G. Wells 'The Time Machine') and as presumably the highest ranking Turelim seen in the game, the Tomb Guardian inherited the name. The "Morlock" name was first used to refer to the Tomb Guardian in a preview in Official PlayStation magazine and subsequently became associated with the character. Despite this, later official sources refer to the character as the "Tomb Guardian". In Debug menus the term "Morlock" is used to denote the area between the Ruined City of the Dumahim and the Oracle's Cave, presumably relating to the entrance to Turel's Clan Territory which was intended to be located there.
The Tomb Guardian and the circumstances surrounding his battle and ability changed a number of times during the course of development:
Several screenshots and footage from trailers depict a prototype Melchahim vampire on the platform instead of the Tomb Guardian
In the Soul Reaver alphas exposed in 2020 the Tomb Guardian is little different from a regular enemy - he has no dialogue, no revived vampire powers and grants no ability. The wraith blade itself grants the ability to fire Reaver bolts and it's unclear how the ordinary projectile was meant to be gained, but the Tomb Guardian is still a prime candidate.
Similarly in early betas, the Reaver is already equipped with projectile ability and Raziel needs to devour the tomb Guardian's soul to get the projectile on its own
The later betas have Raziel use the model of the Force Glyph as a representation of the ability gained upon the Tomb Guardian's death.
Finally the retail version grants the Telekinetic force projectile relic.