And the event card confuses me. We just build our usual decks, then add 6 random cards, and remove them before the duels, or what?
The confusing part actually starts when you try and use the event efficiently!
As an example, take this as your deck:
4vc 4vc 4vc 4vc 4vc 4vc 4vc 4vc 4vc 4vc 4vc 4vf 4vf 4vf 4vf 4vf 4vl 4vl 4vl 4vl 50u 50u 50u 50u 50u 55m 55v 55v 55v 55v 55v 562 562 562 562 562
As it is, this deck doesn't work, so you will drop the acceleration and the Armagio in the first round. Your deck might lose against fast Sanctuary or a sanc stall, or something like this. So if you face that, you will switch the BH's for accels and beat the crap out of that stall.
// It's just an example, didn't think it through at all
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Edit: another, more earthy example:
You can build this war-legal deck: (take a look at the 50% rule)
4vh 4vh 4vj 4vj 4vj 4vj 4vj 4vj 52q 52q 55q 58o 58o 590 590 590 590 590 590 593 595 5aa 5aa 5c1 5f6 5if 5lm 5on 5on 61q
By just adding 6 random earth cards, and remove them when you fight your opponent.