need help with animations and special effects

As the title says I need some help with animations and special effects.
How can u put a special effect under a unit? Like eg the dark summoning model?
How can u loop animations, like eg I want a lich to stand in a circle of power and loop his channeling animation until a timer expires

make a second rigger that runs every (lenght of Liches channeling animation) seconds
it runs only if the timer didnt expire
and for actions use play liches channeling animation

(im nto sure but i think some animation dont need this and you yust use a action
Animation - Play units .... animation

well try it first with the actions
Play liches channeling animation
and after the timer expires
Reset liches animation

if nto then try that every ... seconds play liches channeling animation trigger

its easy just attach to the orgin as shown here:
and it will be under the unit.

I think that the liches channeling animation lasts as long as you want it to, so when you want it to end use the trigger to end a units animation.

of course you might need a second trigger thats event is as long as your countdown timer is, and then use that action to stop your liches animation.

Hope i didnt confuse you. good luck with your map.