before you will try anything have a look at what you are messing with .anim dont contains animations as they are Animations of models are stored in M2 as Block of waypoints for bones https://wowdev.wiki/M2/WotLK#Skeleton_and_animationso ...You cant add new Anim thru M2mod since there is No tool for adding anims yet except MDLVIS that is useless for such situation ( char model has like 260 bones +/- and mdlvis is limited by 60 [ ok MDLVIS may not but tool that you need for conversion before you can enter mdlvis is actualy limited so you wont be able to use this method ] )and btw mdlvis is no miracle too ... even when its able to make anims i would never use this way i would rather make new tool on my ow then this But you can still have a look viewtopic.php?f=20&t=5536
What model it is Where you took itWhat Expansion its fromothervise i think its playback speed
and can you finaly tell me what are you trying to do since alexstrasza is without unchange LK<>Cata ? ( except eye texture ? )