Don't take the funny ratings as indicative of anything, I just find this exchange highly amusing. Anyway, since Janus seems to love them so much.
The Sacred Rules of Engagement of Divine Duels
1. Both gods must agree to a duel for it to be in any way effective and binding. The only other way to directly harm other gods is by inducing domain loss.
2. Challenging another god to a duel costs a generic action. Agreeing is free.
3. Duels may be either until death or domain loss (specific or random domain, agreed on beforehand).
4. Outcomes are determined randomly, (dice roll) though domain affinity and current condition of the god (e.g. trapped within a prison of his own making), may rarely be taken into account.
5. A location for the duel may be specified and will effect the outcome. If no location is specified it takes place in a unremarkable corner of the cornerless Aether.
6. Oaths or promises may be included in duels, with the loser being bound to do some thing or forbidden from doing some other thing. Try to keep this fun and flavourful, not make the games un-fun for the other duelist. As such, can easily be vetoed by the gm, even if the other player agrees to the condition.