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When Rise of the Hobgoblins enters the battlefield, you may pay {X}. If you do, create X 1/1 red and white Goblin Soldier creature tokens.
{R/W}: Red creatures and white creatures you control gain first strike until end of turn.
When the enters-the-battlefield ability resolves, you choose the value of X, pay for it, and put the tokens onto the battlefield. You can activate mana abilities to pay for {X}, but no one can cast spells or activate abilities in response to this choice.
