hi! dirk gives you your first (small) spike, you can either go straight up for duskblade or eclipse to snowball your lead or you can go after dirk directly into hydra if you have a massive lead. so you get early damage and the opportunity to choose what to build next.
scrubnoob meantions this build in his season 13 item guide and i simply put it to showcase in here.
idk why he builds tiamat over dirk first since dirk has more raw damage (tiamat lets you clear faster tho). i'd buy dirk > eclipse > full hydra instead of tiamat > eclipse > hydra...