Viridian Corrupter
Creature — Phyrexian Elf Shaman
Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
When Viridian Corrupter enters, destroy target artifact.
Matt Cavotta
Rulings
If there are no artifacts on the battlefield when Viridian Corrupter enters the battlefield, its enters-the-battlefield does nothing. Viridian Corrupter will simply enter the battlefield.
(wotc • 2011-06-01)
The enters-the-battlefield ability is not optional. You must target an artifact you control if there are no other artifacts on the battlefield.
(wotc • 2011-06-01)
Rulings
If there are no artifacts on the battlefield when Viridian Corrupter enters the battlefield, its enters-the-battlefield does nothing. Viridian Corrupter will simply enter the battlefield.
(wotc • 2011-06-01)
The enters-the-battlefield ability is not optional. You must target an artifact you control if there are no other artifacts on the battlefield.
(wotc • 2011-06-01)