Four legendary founders. Four boarding school houses. FOUR SPECIAL RULES FOR ARMIES ON THE BATTLEFIELD!

1. WARDS AGAINST APPARITION: teleportation cannot originate or terminate within the castle walls.
2. ANTI-FIREARMS JINX: melee weapons and psyker attacks only inside Hogwarts. Projectiles that cross the curtilage wound at a penalty.
3. ESCHERIAN GEOMETRY: vector addition is non-commutative, congruence isn't, and navigators improvise directions at their peril.
4. STAGE HAZARDS: as appropriate.

Let's all have fun and play together!