Simple Explanation:
During Round 1 of the Underworld Tournament, at least 50% of the cards in your deck must come from
ONE of these elements:
.
This is because the "1" in "Round 1" is an ODD number. All rounds with ODD numbers must have at least 50% cards of
ONE of these elements:
.
During Round 2 of the Underworld Tournament, at least 50% of the cards in your deck must come from
ONE of these elements:
.
This is because the "2" in "Round 2" is an EVEN number. All rounds with EVEN numbers must have at least 50% cards of
ONE of these elements:
.
Rounds 1, 3, and 5 are ODD rounds. This is because 1, 3, and 5, are ODD numbers.
Rounds 2, 4, and 6 are EVEN rounds. This is because 2, 4, and 6 are EVEN numbers.