Some arenas are just too small to duel properly. If you cant ascendo without hitting the ceiling or if the spell always reaches a wall no matter where you cast it, the arena is clearly too small. This goes for both 1v1 minigame and challenges, the arenas being the castelomagia for both, dueling tables for challenges, the new beach map for 1v1, the great hall arena for 1v1 has a small ceiling etc. you get the idea.