7. Keywords and effects
Assault
Units that hit harder when they attack
A unit with has +1 while it's an attacker. Some say a number, like Assault 2, and get that much instead.
Only while attacking
The bonus lasts as long as the unit is an attacker, and no longer. Move (2 ) onto a battlefield where your opponent has units, and it fights with 3. Sitting in your base, or keeping a battlefield against your opponent's attack, it's a 2.
Its lethal damage goes up too. While it's attacking, a unit with 3 Might needs 3 damage to die, whatever the number on its card.
Adding up
Assault from more than one place adds up. says "Give a unit Assault 3 this turn." Play it on a unit that already has Assault, and it has Assault 4: +4 Might while it attacks, until the end of the turn.
Try it
Attack with a unit that has Assault, then keep a battlefield with it, and compare its Might.