I can't imagine Foul would summon anything unless there had been serious distance created first. He's only ever really done it personally off-screen (bringing back Elena and the giant Raver that had killed the Seareach giants) and the Ravers have only done it in siege situations. No doubt he could pull it off himself since he gave them the power to do it in the first place (he created the Illearth Stone and all) but it's not an immediate process and he's not an idiot.
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We clasped our hands, our hands in praise of a conquerors right to tyranny