Units gain experience from expeditions and combat and level up on a fixed ladder. The ladder is defined up to level 12. In this build a unit stops at level 5 (the game's current-build cap).
At a glance
The XP ladder
The experience required to reach the next level climbs on a roughly quadratic curve. The full ladder, one level per line, is in At a glance above. The table holds one more value, 9'457, for level 12 itself, where there is no further level to reach.
The level-up prayer
The mana-stone type required climbs with level. The grade and the amount for every level are in At a glance above.
Stones per prayer
The base quantity cycles 4 / 24 / 72 across the whole ladder, independent of the grade band.
Offering tiers
When you pray you also choose an offering tier. The tier trades mana-stone cost against the size of your stat gains. See At a glance above and the Talents article.