Update:
I learnt that animation is cufellbst_atkb. (that fellbeast moves his legs like riding a bicycle while swooping on enemies)
in ini files(fellbeast.ini and w3d.big.) there is an cufellbst_atkb and game using it.
There is few mods(dagor dagorath and see mod) applied that animation i wanted.
And i didn't see any different attack files.i . i only saw rubble and dying animations on their files.
I worked on fellbeast.ini, weapon.ini. weaponsets, locomotors, commandbutton and commandset. I didn't see any change.
i looked bfme 1 too. so this animation is already in game but i can't activate it. .
I tried everything i found on internet about anims. A huge failure . What should i do?