Melancholia

[Agema]

On casting melancholia, in order for a unit to desert:

1) DRN must exceed morale.
- and -
2) DRN+9 must beat DRN+MR.

Thus higher Mor and MR are less likely to desert. Cast against units with 10 Mor and 10 MR, you'd only cause about 5% to desert. Catch them in a moment of morale weakness (e.g. starving), it would be fairly devastating, about a third might desert.