Each player investigates. (To investigate, create a colorless Clue artifact token with ", Sacrifice this artifact: Draw a card.")
"Before you know it, they've pulled you in."
-Grie, Goblin Fixer
When Obalt Inspector enters the battlefield, you may counter target spell with converted mana cost X or less, where X is the number of artifacts you control. (To investigate, create a colorless Clue artifact token with ", Sacrifice this artifact: Draw a card.")
"Curiosity never hurt no one!"
-Enk, Battle Scholar
When Obalt Inspector enters the battlefield, investigate, then counter up to one target spell with converted mana cost less than or equal to the number of artifacts you control. (To investigate, create a colorless Clue artifact token with ", Sacrifice this artifact: Draw a card.")
When Obalt Inspector enters the battlefield, investigate. If you do, counter target spell with converted mana cost X or less, where X is the number of artifacts you control. (To investigate, create a colorless Clue artifact token with ", Sacrifice this artifact: Draw a card.")
Whenever an opponent casts a non-creature spell, investigate. (Create a colorless Clue artifact token with ", Sacrifice this artifact: Draw a card.")
"Curiosity never hurt no one!"
-Enk, Battle Scholar
I'm a little wary of the power level of Violent Curiosity, which is meant to be reminiscent of Rhystic Study and similar effects.