I went ahead and changed the mechanic of the unupped version and changed the upped to compensate. Beartrap deserves to be judged on its own merits; my apologies, I didn't see that one in the recent archives when I was making this one up.
And Poison Trap isn't immaterial exactly, it just can't be stolen...mostly because I'd think it would be freakin' hard to uninstall one and reinstall it in something else. Mostly, though, it's a balance for the fact that it's a card that does nothing if the other player doesn't target your permanent. (Edit: And since this is a
card, protection for the owner from taking damage from using his own steals.)
I'll try and draw up something for art before it goes up, then. How hard can it be to draw a needle with a blob of liquid on the end anyway?
Edit2: Added art.