When this Case enters the battlefield,
investigate (To investigate, create a colorless Clue token. It's an artifact with ", Sacrifice this artifact: Draw a card.").
To solve — You control three or more artifacts.
(If unsolved, solve at the beginning of your end step.)
Solved —
, Sacrifice this Case: Put four +1/+1 counters on target noncreature artifact. It becomes a 0/0 Bird creature with
flying (This creature can't be blocked except by creatures with flying or reach.) in addition to its other types.