You could go Darkness/Aether, with steals (simply steal your opponents pillars pendula) and mindgates.
I don't know if I can participate in this tourney, but I have already made some nice decks.
Sad that you can't use 6 pendulums only, I have designed a very nice Darkness/Life deck:
5c2 5c2 5c2 5c7 5c7 5c7 5c7 5c7 5c7 5uq 5uq 5uq 5ut 5ut 5ut 5ut 5ut 5ut 606 606 606 606 606 606 606 606 606 606 606 606
Yes, The ??'? are Darkness pendula.
This is one of those decks that have gotten really better with the introduction of pendula.
But in my pendula testing streak, this is my favourite (??'? = fire pendulum):
5f7 5f7 5f7 5f7 5f7 5gi 5gi 5gi 5gi 5gi 5gi 5gi 5gi 5gi 5gi 5gi 5gi 5gi 5gi 5oi 5oi 5oi 5oi 5oi 5om 5om 5om 5om 5om 5om