No you don't lose EXP.
No you don't gain EXP.
No you can't loot their money.
You don't need permission from the other guild to declare war.
You don't get any killing points (that's probably for PvP instead of GWs).
You should be able to GW anywhere.
You opponent's guild name will turn red.
You can war with more than one guild at time.
After declaring a war, there is a 5 minute wait before war starts.
Guild wars last for one hour.
There is a cooling period after guild wars for one hour (I think).
You cannot invite people into your guild during a guild war.
You cannot buff/heal/revive people in the opposing guild.
Only guild masters/admins can declare wars.
Hmm that's all I can think of.
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