In my Depths deck, I run 4x eidolon of rhetoric since the misstep restriction. When the card lands, it wins games. If I can turn 1 stick it, I usually beat PO and xerox that give my deck fits. The problem is I often only have 1 or 2 mana on turn 1, and then lose before I get a turn 2 vs something like PO. This shaves that effect's cost to 1 mana (and can't be plowed) - this is a welcome addition to my deck.
This card is basically good in any deck that wants to build a 50-card-or-less deck (4x this, 4x wraith, 1x git probe, X cantrip). In decks that want multiple pieces or several options, I think this card is just 4 less spots for gas. Keeping a hand with this as your first or second land drop, hoping to see one in the top 5, is almost always worse than just mulling. The times you use it turn 0 and wiff on a land you wanted, it will cost you games.
@cutlex This makes no sense to me. Shops was tier one and borderline oppressive before WAR came out. Now after WAR and M20, they have +1 Karn and +1 Forge...and they drop to tier 2?
Edit - I'm late to the party. I read further and saw several folks said this exact same thing!
@dracomnisgt The list in that link is basically ad nauseum tendrils with painter/stone jammed in. It utilizes Reap well, but that doesn't go with REB. REB is good in general, but I also dislike calling "blue" on painter as you now allow the opponent to pitch any card - even land - to FoW. I'm thinking of building more around Painter and cards synergistic with a single color choice. Something like naming "White." Havoc becomes a cool card because for 2 mana, you get a 1-sided pyrostatic pillar. 10 spells and you win. You can also play gloom. 3 mana and it's a 1-sided triple sphere effect. By using black/red cards, you also get all the best tutors and goblin welder + goblin engineer.
I'd suggest R/B because of the welders and tutors, but you could try red/white. White has 4x enlightened tutor, great foils to black, and that could let you utilize reap too if you go RGW. The design space is wide open. I wouldn't take a deck with one strategy and jam painter in it. Build around painter and make the grindstone an incidental win.
I actually considered painter with the grindstone kill as secondary. There are a host of strategies you can use that just wreck a mono-colored deck. Think white and Gloom, black and CoP black/reap, etc. You can make a great value-town deck with painter where the grindstone is just a bonus "oops, I win". I think it's viable with the right thought put into it - painter itself is immune to null rod effects.