For wizard duels, the set up should be as such:

Entering the tournament the wizards are barred any magical items or assistance. Likewise they are analyzed to ensure no such things or buffs exist coming into the duel.

The duel is structured in three segments

Phase 1:
You get X rounds to cast spells that effect yourselves
Phase 2:
You get Y rounds to cast spells that effect the environment/summon (but nothing directly attacking or hampering your opponent. (Example rock to mud under their feet is disallowed, but fogging the arena is.)
Phase 3:
Anything goes.