Limitations of the spell:
- In order to be able to veil units Foolamancer must be in the stack that is being veiled.
- The spell cannot be cast on the enemy's turn.
- Foolamancer must not be linked with other casters.
- When veiling cities, only one city can be veiled at a time.
Spell name is Crypsis.
Veil can blown if enemy warlords are present in the same hex as a veiled stack. The more units are in a veiled stack and the more enemy warlords are in the hex the higher are chances of blowing the veil. It is not clear whether regular units have less chances to blow a veil or whether they can blow a veil at all.
Apparently the veiled stack cannot be made completely invisible. Instead it appears to enemy units as something else.