While Goblin Tunnels is in the staging area, each Goblin enemy gets +1

Forced: When Goblin Tunnels is explored, the opposing team searches the encounter deck and discard pile for a Goblin enemy with cost 1 or less and adds it to the staging area. Shuffle the encounter deck.

When Revealed: Each engaged enemy makes an attack. If no attacks were made this way, Massing in the Deep gains surge.

Shadow: Each enemy engaged with you gets +1