First, you skip your draw step so you'll never naturally draw a card in your life again until this is ended
Dealing damage with Lathril makes that many 1/1 Elf Warrior tokens, so anything you can do to modify Lathrils power from either lord effects or auras or enchantments will give you tons more tokens
All four of these abilities are good by themselves, but together they synergize beautifully to keep Sauron on the field, your Army growing, and your hand fresh
As long as you have consistent food creation through means like Sam, Loyal Attendant, Trail of Crumbs can draw a ton of cards
As such I tend to avoid it when I have a good solid deck and run it when I am worried my list is a bit too far off optimal
She generates tokens when she deals combat damage and drains all opponents when you tap ten Elves