Obsidian-works enters the battlefield tapped unless you sacrifice an artifact.
: Add or to your mana pool.
Sacrifice Obsidian-works: Add or to your mana pool.
, , Sacrifice Obsidian-works: Target player gets a poison counter.
: Add 
or 
to your mana pool. or to your mana pool., , Sacrifice Obsidian-works: Target player gets a poison counter.
