lvl 5 Hamaya isn’t 3 times stronger than Possession, though.
Possession hits 2 times per second and the base damage is 923 at lvl 10 vs Mikos 1013 of lvl 5 Hamaya.
CD is 20 secs on Possesion vs 35 secs on Hamaya, only the number of hits,the holy property damage and the skill duration make Hamaya a little superior, but if you can get 14-15 targets into Possession, the amount of total damage should be ± equal over time.
Also, the attribute damage increase is a lot cheaper on Possession than Hamaya (12,3 m in total if attributed until 100%), so unless you got a lot of $$$ you may account a higher attribute% onto Possession also.
Aside that, a question: Did anyone check if Clap prolongs the duration of Tet Mamak La’s skulls? The skill seems to be forgotten a lot I believe, so maybe noone tested it beforehand.
And the same for Kagura Dance: does it increase Tet’s skull damage?