as a player of RTS,I can’t help but cringe. I use the tactic of a turtle merchant. to heck with rune crafting, earth manipulation. He could have closed off entrance to his valley all the way to the top of the mountains. allowing the time to purchase 100 farmers, 100 gatherers , 100 hunters, 100 scouts. then use the same method to make entracate caves in the mountains leaving the valley. next I would tunnel all over for hundreds of miles around the valley for surprise attacks and places to sleep during the day. next would be lava foundry,lots of them. replanting the forest that would be gone after a few weeks. the only goblin making babies would be the 4 armed worker,then make him a leader. all regular goblins would sent to man outposts with same 100 farmer,100 gatherers, 100 hunter,100 scout scheme. all extra food would be delivered back to main base. after a while all foblins would be accompanied by 10 diggers to create small goblins bands everywhere. the main town would be comprised 4 armed goblins. all replaced by sacrifice to seeded VI. Most buildings would wait to be placed inside caves as the army of miners dig out the space