Kollector, Tribute Seeker

When Kollector, Tribute Seeker enters the battlefield, you may search your library for an artifact card with converted mana cost 2, reveal that card, put it into your hand, then shuffle your library.
Whenever Kollector, Tribute Seeker attacks, each opponent loses X life, where X is equal to the number of artifacts you control. You gain life equal to the life lost this way.