I got Aeron's Chosen once and upgraded him into a Marksman. Aeron's Chosen is awesome because with the Heal After Combat feature (which works even against nonliving enemies, unlike Cannibalize), you literally cannot be killed by a swarm of mooks. Anyway, I declared war on Hyborem and moved Aeron's Chosen in by himself, and it turned out that Hybo had stored up about 250 Manes in Dis (the AI obviously still doesn't understand how to settle Manes). All 250 manes suicided on me in one turn. Aeron's Chosen had Valor and a Great Commander attached, so he got 750xp in one turn! I think he ended up with over 1400 xp in that game, and ran out of promotions to take.