Sealord's Maw (BSS05-114) [Strangers in the Sky]

[LV1][LV2] During Either Attack Step

If one of your opponent's spirits that costs 2 or fewer attacks, place a core from the void onto this nexus. If one of your spirits that costs 2 or fewer attacks, destroy this nexus.

[LV2] During Opponent's Attack Step

When your opponent uses a magic card from their hand, place a core from the void onto this nexus after its effect resolves.