Is Chamber Sentry legal in Standard, Modern, and Commander?

Chamber Sentry is legal in: Modern, Pioneer, Legacy, Vintage, Commander, Historic.

What type of card is Chamber Sentry?

Chamber Sentry is an Artifact Creature — Construct. Its oracle text reads: "This creature enters with a +1/+1 counter on it for each color of mana spent to cast it. {X}, {T}, Remove X +1/+1 counters from this creature: It deals X damage to any target. {W}{U}{B}{R}{G}: Return this card from your graveyard to your hand."