What does mark of knowledge do? What makes abilities different to tomes?

[Pulse Of Me]

What does it mean by acts as tomes? What are tomes?

[Letari]

Tomes are the things dropped after bosses/elites die that let you pick new abilities or upgrade existing abilities. Mark of Knowledge allows you to choose from the entire ability pool rather than 3 random ones that normally appear on tomes when playing with everyone aside from Sage.

[Ulyaoth]

Normal Elite Drops are Scrolls of Mastery (golden Scroll) described by Letari.
One Tome of Mastery (golden Book) per Map can be unlocked via Quest.

- Scrolls give you a random selection for Abilites and Upgrades
- Tomes let you choose Abilites and Upgrades

Visual Difference - Category Special
https://hot.fandom.com/wiki/Pickup