This is actually pretty easy given that the tombs are levels. Simply replay the tombs, which have no enemies and avoid hurting yourself. I prefer replay elite so you have all your tools still which makes this easier
Thanks to Wintr17:
It might be helpful to add the level names of the tombs:
Ancient Cistern
Voice of God
The Red Mine
House of the Afflicted
Catacomb of Sacred Waters
Baths of Kitezh
Chamber of Exorcism
Pit of Judgement