Petty good concept, but without good instuctions most people don't understand whats going on.
Thats why it worth 4 or 5 but most people gaves 3 and 2.
I give it a 5.
Don't brother with offset for the last two duel, they stop when they fire, so direct fire does works.
For a really serious challenge, try to duel Loki with "VOID" on Valkyrie.
After that, for a "Are you kidding?" challenge, try Act20 with same "VOID" on Valkyrie, it is possible but require godlike skill.