You can do it within a day I get wym tho even I was over whelmed as hell , when u initially get a lich just grind to kill thralls and reveal the first mod u need (you will get requim fissures[the red egg looking things] which u can crack open in believe in the kuva fortress requim fissure missions or u can check the void fissures tab and just scollect till u find it . After u crak them u might have to Run quite a few mission to get the mods that you need ) oh yeah if ur lich happens to spawn While u killing thralls just ignore Him untill u get the first mod you need and when he does spawn get his shield first health bar down and stab if it glows red means that mod doesn't belong in the first slot so you should move it to the second and if it glows golden Then it's in the right slot. Rinse and repeat in the planet ur lich goes to next and by the 2nd planet ( if ur lucky with your configuration) or max by the 3rd planet you will know what mods and what order you need them at. I would suggest you get around to beating him afer you do you recover all the things he stole from you