When you use {Lothel Troll}'s ability while {Library of Leng} is on the field, and you choose to put a card from the top of your library into the graveyard, Lothel troll doesn't gain a counter correct?
It does.
LoL replaces the discard to graveyard with a discard to top of library, but the discard still happens.
Wait. I misread at first.
Why are you putting a card from the top of your library into the graveyard?
I did read it wrong, I thought it said that you put the card from the top of your library into the graveyard instead of discarding 😅
To vs from in old wording. Such a small detail. However: always follow Oracle rules text, to prevent losing the game from a {time walk}, or getting an abusive {regeneration}.