(Hollow Forge isn't a spell.)
Hollow Forge enters the battlefield tapped.
, : Tap target artifact with converted mana cost X or less.
: Add to your mana pool.
: Add or to your mana pool. Each opponent gains 1 life.
, 
: Tap target artifact with converted mana cost X or less.: Add 
to your mana pool.: Add 
or 
to your mana pool. Each opponent gains 1 life.
