These are great ideas and great pictures. Maybe someone should do stats for using them in various editions?
For example for B/X (my preferred edition)
Sis'thik Crusher
by JohnL73
Armour Class: 4
Hit Dice: 5+5*
Move: 60'/burrow 30'
Attack: 2 claws/1 bite
Damage: 1d6/1d6/2d4
No App: 1d6/1d6
Save As: Fighter 5
Morale: 10
Treasure Type: D
Alignment: Chaotic
Intelligence: Low (7-8)
XP Value: 400
Sis'thiks that die and are buried with unsatisfied vengeance may come back as Sis'thik Crushers, also known as Lizardman Undead Crushers. Sis'thik crushers can hide underneath the sand indefinitely (being undead they don't need to breath). They can move through the sand, slowly but stealthily.
Sis'thik crushers are immune to normal weapons - silver or magic weapons or spells are needed to hit them.
Their torsos are weirdly heavy, as if their chests are filled with lead. If a Sis'thik crusher hits a small or medium opponent with both claws, it will hurl its torso onto the opponent who must make a save vs paralysation or be crushed to the ground, taking 2d6 initial crushing damage and being pinned underneath. The Sis'thik crusher can continue to pin down an opponent, immobilising it and doing an additional 1d6 crushing damage per round until the Sis'thik crusher decides to move off.
Edit: Sis'Thik crushers can be turned by clerics as if they were mummies. Also as undead they are immune to sleep, charm, poison and disease.