Hilltop Weir

Fortify {3}({3}: Attach to target land you control. Fortify only as a sorcery. This card enters the battlefield unattached and stays on the battlefield if the land leaves the battlefield.)
As long as fortified land is untapped, whenever another player adds {u} the first time each turn, add {u}. Otherwise, whenever a blue spell would resolve and no other blue spell is on the stack, instead it doesn't. (It remains there, has no effect,