How to Find Tauren Chieftain Secret Boss ?

Still remember with Dota 6.59b map ? In Dota 6.59b there is a new quest. The new quest is you should to find 4 totem (Sentinel) or IceFrog (Scourge) and place the totem/icefrog  on the top-left corner of the map (for Sentinel). After you place the 4 totem, you will meet with Tauren Chieftain Secret Boss and you can against him. After you kill him, you will be get Axe of the Chieftain.

I've try to find the totem/icefrog and I can do it. But, I can't place the totem/icefrog in the right place :( Btw, can you find and against Taurent Chieftain Scret Boss ?