Thran Weaponry [Urza's Legacy]

Echo {4} (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.)
You may choose not to untap Thran Weaponry during your untap step.
{2}, {T}: All creatures get +2/+2 for as long as Thran Weaponry remains tapped.