EC needs explaining with examples.
Team
wins two matches and gets 12 salvage.
They choose to forfeit 6 salvage. The EC will give 2 tokens per 3 sacrificed salvage, so it will give them 2*(6/3) = 4 tokens.
They then change their mind and sacrifice 11 salvage. 11 isn't a multiple of 3, so only 9 of the 11 sacrificed salvage will give tokens. They would receive 2*(9/3) = 6 tokens now.
They decide they like multiples of 3 and increase the sacrifice to 12. They would receive 2*(12/3) = 8 tokens.
Team
can't sacrifice more than 12 salvage because that's all the salvage they have.
Sacrificed salvage does not have to be from the same deck; e.g. for 6 forfeited salvage, they can sacrifice 2 salvage from deck A and 4 from deck B.