You may have started to notice several cards from the Jade Faction in the the upcoming expansion Mean Streets of Gadgetzan summon Jade Golems.
The Legendary card from Jade for example, is Aya Blackpaw.
As you can see from the card text you summon a Jade Golem from both the Battlecry and the Deathrattle of this minion.
Jade Golems are minions that start at 1/1 when you summon the first one. They then grow +1/+1 in stats for every extra Jade Golem you summon.
So, Aya Blackpaw will summon a 1/1 when you play her. Then when she is killed off you will see a 2/2 spawn. (unless you have summoned more in the meanwhile).
It’s not clear yet how many cards will summon Jade Golems in a single game. The 30/30 is possible, but just used here as an example.
With Brann Bronzebeard doubling up the battlecries there is some potential for a lot of Golems hitting the board. We will have to see how it plays out when the new expansion is released in a few weeks.