If you don’t have an artifact card in your library while resolving Tezzeret’s first ability, you’ll reveal your library and then randomize it.
2017-02-09
The effect of Tezzeret’s third ability lasts indefinitely.
+1: Reveal cards from the top of your library until you reveal an artifact card. Put that card into your hand and the rest on the bottom of your library in a random order.
−3: Target opponent loses life equal to the number of artifacts you control.
−8: Gain control of all artifacts and creatures target opponent controls.