Elisho's Barrier:

If successful, the caster may increase the DC needed to cause any harm to them or their artifacts by half the amount of magic points spent on casting this spell, rounded up. The upkeep cost of this spell is equal to a quarter of the number of points spent, rounded down, to a minimum of 1. Alternatively, this spell may be cast on a unit at the start of a war session as a war spell, increasing their HP equal to the amount of magic points spent; up to a maximum of half their base HP, rounded up. This "Barrier" HP cannot be restored by any means, and disappears at the end of the war session.