Well I guess people are now finally catching on and showing some interests so here is a list of potential items that can be gotten. But here are some facts:
1. You can only get them from the Primevil Lich spawn
2. There is a chance that 1 item will respawn during each tier of the spawn starting from the beginning. Sometimes you get only 1 item respawn from the entire spawn. Sometimes nothing spawns at all.
3. When the boss is killed all environmental introductions disappears.
Items can be gotten are:
1. Vat pieces (6 pieces in all)
2. Rack pieces (8 pieces in all)
3. Levers (8 colors)
4. Ank (2 pieces)
5. Giant Head Skull
6. Iron Maiden
7. Nameless mounted pixie statue
8. Large green crystal with pedistal
9. Large black spikes
10. Small black spikes
11. Rune symbols (large, small, small red)
12. Dragon head trophy (8 pieces in all)
13. White Lava tiles (some animated, some not)
14. Wall pieces (3 types)
15. Grave stones (many shapes)
16. Grave dirt patches
17. Brambles
18. Fallen branch
19. Piles of skulls (many shapes)
20. Banana Trees large and small
21. Death Vortex
22. Pillary pieces - many
23. Chopping block pieces (blocks, axe)
24. Giant cacti tree
25. Red Sparkles
26. Red and Black Bone Containers (from solving the lever puzzle)
27. Grusome Standard different graphic than Level 5 Doom Arti
28. Giant Demon Skulls
29. Dark Blue Rocks and Boulders
There might be more so add if you know more.
1. You can only get them from the Primevil Lich spawn
2. There is a chance that 1 item will respawn during each tier of the spawn starting from the beginning. Sometimes you get only 1 item respawn from the entire spawn. Sometimes nothing spawns at all.
3. When the boss is killed all environmental introductions disappears.
Items can be gotten are:
1. Vat pieces (6 pieces in all)
2. Rack pieces (8 pieces in all)
3. Levers (8 colors)
4. Ank (2 pieces)
5. Giant Head Skull
6. Iron Maiden
7. Nameless mounted pixie statue
8. Large green crystal with pedistal
9. Large black spikes
10. Small black spikes
11. Rune symbols (large, small, small red)
12. Dragon head trophy (8 pieces in all)
13. White Lava tiles (some animated, some not)
14. Wall pieces (3 types)
15. Grave stones (many shapes)
16. Grave dirt patches
17. Brambles
18. Fallen branch
19. Piles of skulls (many shapes)
20. Banana Trees large and small
21. Death Vortex
22. Pillary pieces - many
23. Chopping block pieces (blocks, axe)
24. Giant cacti tree
25. Red Sparkles
26. Red and Black Bone Containers (from solving the lever puzzle)
27. Grusome Standard different graphic than Level 5 Doom Arti
28. Giant Demon Skulls
29. Dark Blue Rocks and Boulders
There might be more so add if you know more.