cards that end the turn mtg (Glorious) of Amonkhet: Exclusive Preview MTG : How works Sundial

They are played in many formats, such as Vintage or Old School, but also in Commander

Its drawback may look like its very punishing and can allow the opponent to surprise you via a mid-combat spell, but I never really saw that scenario play out since its damage prevention ability is a a conditional static ability so as long as its on when damage is dealt, it wont be prevented. (Thank you, @fenaris!) It usually plays out somewhat like a colorless Ashenmoor Gouger / Chimeric Idol where you typically dont bother trying to block with it (why am I blocking with my aggro guys anyway?) and, if need be, you cast a spell pre-combat to activate it (typically I used a large coin, like a quarter, to denote whether it was on or off)

Can planeswalkers be commanders

They're also cumulative with other effects that let you play additional lands, such as the one from Urban Evolution