This is the Jade Lightning HS Shaman Card from the upcoming expansion Mean Streets of Gadgetzan.
It’s a Shaman class spell and the card text reads: Deal 4 damage. Summon a Jade Golem.
Jade Golems are minions that each time you summon one it’s stats will increase by +1/+1. So, your first Jade Golem is 1/1 as per below, then 2/2, and so on.
You can get Jade Lightning by opening packs from the Mean Streets of Gadgetzan set.