- A reference guide and manual in Russian for Heroes 3.

Adel has a similar effect, but instead of increasing attack/defense, it increases the blessing bonus (per unit) given to creatures of that level.

The bonus also depends on Adel's level. Approximately as follows:
Level 1 - at levels 1-12-23... (every 11 levels)
Level 2 - at levels 2-18-34... (every 16 levels)
Level 3 - at levels 3-18-36-51... (every 15/18 levels)
Level 4 - at levels 4-16-32-48... (every 16 levels)
Level 5 - at levels 5-15-25-35... (every 10 levels)
Level 6 - at levels 6-12-24-36... (every 12 levels)
Level 7 - at levels 7-14-21-28... (every 7 levels), possibly with a +1.5 damage increase instead of +1, as with the other levels.
Perhaps there is a complex formula for calculating this.