This is the Sunkeeper Tarim HS Paladin Card from the Journey to Un’Goro expansion due for release in April.
It’s a Paladin class legendary minion and the card reads: Taunt. Battlecry: Set all other minions’ Attack and Health to 3.
You can get Sunkeeper Tarim by opening packs from the Journey to Un’Goro set.
*This is a really good card in a control deck. It fits the Paladin theme well following on from other cards with similar effects.