Combat:

The following are the rules for combat (attacking, defending, etc.):

Attacking:
Roll 1 D20.
If you roll your foe's defense, or higher, you will hit your foe. Always add any "Offense" bonus to your attack-roll.
When you successfully strike, your foe will then roll to defend. See: "Defending" (below)

Instant defeat:
If you roll a 20 when attacking an enemy, roll again. If you roll another 20, you instantly defeat your foe and gain a level (with 0 experience towards advancing to the next level).
Each time you level, your Life-points are restored to full.
This ruling ONLY APPLIES to player characters. Creatures will only cause x2 damage if a double twenty is rolled.

Defending:
Roll 1 D20.
When you are struck in combat, all you have to do to evade the attack is roll higher than the attacking roll.