So easy to gain 6 armour in Druid, then it's a 1 mana spell deal 6 damage... it's defiantly playable. If not in every control druid deck. This the death knight, earthen scale and the gain 8 armour for 3 mana spell (forgot what it's called) easy to upgrade, very good.
why would this be bad? at worst its like living roots played for damage, which it often was. At best, its a huge tempo swing, and is super easy to power up. Cards like holy smite and arcane shot are on the edge of playability even now (evidenced by holy smite being played to survive in some priest matchups, not always for the velen combo), and this has enough of an upside that it should make the cut in just about every druid deck. the synergy with UI is also very real, because it both powers it up, and UI coin jasper spellstone should clear most boards, and make sure you arent milling cards. Also, the death knight completes this so easily that it will probably be an auto include like living roots was.
Control tool for Druid that is hard countered by a card already teched in Druid heavy metas. Honestly, giving them this is probably fine since they'll need an identity once Jade Idol rotates out next expansion. Control (Taunt?) druid is an alright identity, imo.
But it needs ways to win without Jades, and it can't do that without removal tools. This also attempts to convince you to run cards like Claw, Gnash and Bite, since those also remove minions while buffing this card in the process. Probably won't succeed at it, but it's an attempt, and I appreciate that. If nothing else, a creative and flexible card.