When this Case enters the battlefield, create a 2/1 black Skeleton creature token and suspect it. (It has menace and can't block.)

To solve — You control no suspected Skeletons. (If unsolved, solve at the beginning of your end step.)

Solved — , Sacrifice this Case: Search your library for a card, put it into your hand, then shuffle. Activate only as a sorcery.

Lifelink

When Desperate Bloodseeker enters the battlefield, target player mills two cards. (They put the top two cards of their library into their graveyard.)

Target creature you control gains hexproof until end of turn. Untap that creature. Until end of turn, it becomes a copy of up to one other target creature.

: Add .

, , Sacrifice Mind Stone: Draw a card.

Each other creature you control that's a Skeleton or Pirate gets +1/+1.

Whenever one or more creature cards leave your graveyard, create a 2/2 black Skeleton Pirate creature token. (This ability triggers only from the battlefield.)

: Return Skeleton Crew from your graveyard to the battlefield tapped.

Trample, indestructible

Whenever another creature you control attacks, it gains trample and indestructible until end of turn.

If you would create one or more artifact tokens, instead create those tokens plus an additional Map token. (It's an artifact with ", , Sacrifice this artifact: Target creature you control explores. Activate only as a sorcery.")

, : Create a token that's a copy of target artifact token you control.