Ice Flan

Enter-the-battlefield tappers have existed forever, but the classic ones untap on the opponent's turn, so a Master Decoy or a Sunblast Angel effect only ever bought you one attack step. The stun counter rewrites that math: the tapped permanent stays locked through its controller's next untap step, so a would-be blocker misses two combat phases instead of one, and an artifact mana source or activated ability sits dark twice as long. Six mana and a 5/4 body pay for that extra turn of lockdown, and the trigger reaches only a single artifact or creature an opponent controls rather than anything broader; that narrowness is the cost of the doubled window.

What keeps an expensive blue creature from rotting in the wrong situation is the cycling suite stapled underneath. Islandcycling in particular lets the card double as a two-mana land-fetch when you are flooded on business spells or short on blue sources, so the slot is never truly dead: either you deploy the tapper as a tempo swing or you shred it for the fixing you needed more. That split, a real body with a locking trigger on one axis and a search-your-library discard outlet on the other, is what earns a card this heavy its place at all.