Assuming Marcus beats SR 24 with both spells:
Will save vs DC 24 mythic holy smite 1d20 + 10 ⇒ (17) + 10 = 27
Will save vs DC 24 mythic holy smite 1d20 + 10 ⇒ (7) + 10 = 17
Will save vs DC 24 mythic holy smite 1d20 + 12 ⇒ (4) + 12 = 16
Will save vs DC 24 mythic holy smite 1d20 + 10 ⇒ (5) + 10 = 15
The ice devils are, of course, immune to cold damage, so we won't bother with whether they save or not vs the cold strike....