Where are the rest of the Troll champions?

So Trundle is troll king, KING! So why dont any of his subjects fight with him. We have so many yordels and infinite human characters, speckled with a few oddities here and there. Hell, even the void has multiple representative on the rift. But the Trolls are just seemingly nowhere to be seen, which I find odd since Trundle seemingly wants to expand his influence. When do you guys think we will get some more Troll race champions? Do you even want to see more trolls from his tribe/kingdom?

Edit: Here is an excerpt from his back ground showing he is looking to be a conqueror the rest of the troll tribes, and bring the trolls into a more prominent position within the world. I think it is safe to say he would have garnered a few champions for his kingdom by now.

When Trundle returned to the warband, his fellow trolls bowed to his conquest. Calling his weapon ''Boneshiver,'' he took a moment to enjoy the look of numb shock on his chieftain's face before he caved it in. Seizing command, Trundle announced that there would no longer be chieftains - only a Troll King before whom all of his kind would kneel. The trolls rallied behind their brash, new leader and prepared for the coming war. With Trundle leading the charge, the time of the trolls had finally come.