Why not have unlimited subs? Sure some elements will have more than others but only 5 people will be playing at a time.. Let them have access to the war room so they can particpate in team discussions and give them an award icon or whatever for being a sub on the winning team. You could even have a rule like lose your match, you're replaced by a sub. I think the more people involved in the event the better.
The thing is I want to limit the chance of cheating. If we give 20+ people access to a specific part of the forum, most of them not actually playing in the event, chances are one of them will give information to the enemy. If on the other hand we give access to only 5 people, all of which are playing, chances of cheating is much smaller.
Also the point of limiting was to get teams balanced so that all teams are full, as opposed to a situation where everyone joins the "cool" team. Luckily all teams have proven to be quite popular, and there are no outcast elements.
The reason for having an 18 card limit is so that there is deck variety, correct? You dun wanna see 5 identical decks of all the usual suspects like shrieker rush, mono aether, etc. I think that would be better achieved using special deckbuilding rules eg. max 3 of any 1 card per deck.
Because everything else is new, I'd like to keep the battles and deckbuilding as simple as possible. 6 card limit per deck is the official dekcbuilding rule made by Zanz so I think we should use that in this event. Everyone already knows it so there's less chance of confusion.
"max 3 of any 1 card per deck" special rules should be saved for special tournaments or something.
I'm torn between 12 card and 18 card limit at the moment. On one hand 18 cards lets you build more standard decks, but on the other hand 12 card limit is pretty close to a situation where everyone just takes 12 copies of each card from their element and there's really no choice involved, apart the choices from other elements.