In Defiance, Raziel emerged from Elder's Lair in the Cemetery and after gaining the Dark Reaver, was able to enter Kain's Mausoleum himself, apparently shortly after the younger Kain's exit. Raziel was able to go through Kain's Mausoleum and reach the teleporter to the Light Forge.
Kain's Mausoleum undergoes some radical changes between its Blood Omen and Defiance incarnations; the layout has changed (although some parts are certainly reminiscent of it) as has the colour scheme and there is now a large painting of the Human Kain above his grave.
The Mausoleum in Defiance is filled with small nods to the original Blood Omen; Kain's grave appears in similar fashion to its appearance in Blood Omen, with the lid opened from the inside; The Painting of human Kain grows small fangs in the Spectral Realm and is decorated with Furthark runes which translate as "Here Lies Kain". Further down the corridor, there is also a grate which appears to have been broken, presumably by the younger Kain's escape, and a large bust of the Human Kain.
Kain's human family crest bears a remarkable similarity to his later clan symbol and it may be that symbol was based on it. Remarkably the outline of the clan symbol is also present in the Ancient Vampire Murals of the Scion of Balance found in the Spirit Forge, though this coincidence is less likely to have been directly planned.
Also, in the games "Tomb Raider Legend", "Tomb Raider Anniversary" and "Tomb Raider Underworld", Kain's portrait from the mausoleum can be seen within Lara Croft's Manor.