I'd potentially consider discussing a 2-3 minute wait before you could launch again from the closest FIELD to which you died if it was your countries, but a 15 minutes would turn the arena into a ghost town, I doubt I'd be in favor of any wait, since as has been pointed out, any kind of a wait at all would be unbalancing in the field defense department, Besides, if you want to keep guys from re-upping, you can take down hangers.
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