Most efficient form to summon Trolls in big numbers?

[Viajero]

Originally Posted by Trumanator

Vine ogres make good walls. They're really gem efficient too with an ivy crown.

Yes, but I was asking for other type of units, one that really looks like a green or black tree of some kind with tons of HP, last time I saw it it was Pythium using it in LA aganist my Utgard giants as a defensive wall, cant quite recall the name...