Abilities

Abilities are part of Combat and fall into three groups: basic abilities, spells, and companions. Each ability is learned using a tome, and there are three ways to obtain tomes, by either; receiving the tome as a drop, inscribing the tomb through Inscription, or earning the tomb through Achievements.

Information about spells could be find here: Magic.

Information on basic abilities and companions will be found on this page.

Basic Abilities
Basic abilities fall into two groups: active (activated on use during battle; e.g. penetrative slash) and passive (continuously active while equipped, e.g. accuracy up).

Here is a list:

The following info has been scraped from in game menus as well as other wiki pages and is by no means definitive

also see this page ☀http://eternitytower.wikia.com/wiki/Inscription

Moreover, at level 20 of inscription you can find some more passive abilities.

Companions
Companions are creatures summoned using companion tokens. The ability to summon a companion is earned from Achievements, and the companion tokens are dropped while having no companion equipped in any floor of the Tower(chances are increased the higher the floor, with the number of real players in the players group, and by any other effect on drop rates).