Sleeper Cult Board
The Sleeper board is full of Skulks, including the unique Ritual Skulk, the Flex Skulk, and the Block Skulk.
Sleeper also has a site which rewards the user with 4 Treasure. However, the player must have at least one cultist on any Skulk (including the other cult board Skulks) to use this site. More than one Skulking cultist won’t increase the reward.
The Ritual Skulk lets the player place a cultist on the Start (only) of any ritual track. He must pay the 2 Treasure price at this time. When the Ritual board activates, this cultist does advance to the next stage and gain rewards, because the Skulk is placed before the Rituals are advanced. Of course he must still leave his cultist on the ritual board for the next turn (or longer, if he chose Dragon Ascending). You may be familiar with the Ritual Skulk from the Black Goat board, which also features one.
The Flex Skulk lets you place the cultist as per EITHER the normal Town Skulk or the Ritual Skulk. Your choice. The Block Skulk must be the first Skulk assigned. It acts exactly as a Flex Skulk except no other Skulk can be assigned to its spot! I.e., it blocks other Skulks (hence the name).