Marana infirmux!

Pronunciation guide here. 

Blood (excellent game) has a wonderful series of cultist language phrases and words that I heartily recommend incorporating into your RPG of choice for things such as parts of an eldritch incantation, the speech of the Old Ones or, well, things cultists yell.

Here's a random table!

Roll 1d50:

1. Rud'minuox
2. Rudsceleratus
3. Pestis Cruento
4. Cruo
5. Crunatus
6. Petriacruento
7. Cruentu
8. Cruensseasrjit
9. Cruonit
10. Shaantitus
11. Cruento Pestis
12. Domus
13. Marana
14. Bibox
15. Vorox
16. Cruento Paashaeximus
17. Shatruex
18. Infirmux
19. Crudux
20. Vigra
21. Invisux
22. Maravita
23. Domus-bhaava
24. Acerbus-shatruex
25. Pretaanluxis
26. Odiosux
27. Odiosuu
28. Cruo-stragaraNa
29. PrayaNavita
30. Villomaxus
31. Profanx
32. Profanuxes
33. Exim'ha
34. Tuulenux
35. PraaNsilenux
36. Esco
37. Bhuuesco
38. Desco
39. Bhuudesco
40. Hatanoceo
41. Gero
42. Geropayati
43. Cruonita
44. Infuscomus
45. Malax
46. Caecux
47. Quodpipax
48. Pallex
49. Durbentia
50. Lokemundux

As a rough guideline, roll D2 of these for a yell or exclamation and D3+1 for part of a dark rite or a full spell.

Words are sourced entirely from here: https://blood-wiki.org/index.php/Cultist_Language

Vilomaxus gero malax!