[Edi]

The best fix for the problem of massive use of raiding spells is using a magic site frequency of 25 or less for MP games, then the players will really have to CAREFULLY consider what they use their hard earned gems for. This way summoning anything powerful is a major decision and the role of national units is greatly increased. If you also put research on very difficult, they become even more prominent and you need to carefully consider what to research to maximize your strengths.

Of course, blood nations are more powerful on magic poor maps, but that is not an insurmountable problem either.

On such maps, madcastling is not such an attractive strategy, and massive raiding spell use is not viable at all.

Edi