After determining Initiative, at the beginning of each round, every combatant makes a 2d6 roll and adds their AGI and END to it. This is added to their Defense rank to create their Base Defense for the duration of the round. See the rules for attacks, below, for what this score does. A combatant's Base Defense should be recorded on their sheet.
To decrease the GM's rolling load for this, they may opt to roll just once for each enemy type, or perhaps for all enemies, or all enemies in a specific Arena zone, etc.
If using the optional War Form rules, then AGI and END are not added to the Base Defense, and only 1d6 is rolled.