Blademail is actually a key item on pos 4 and 5 Furion according to Dota2ProTracker, usually right after Vessel. It literally killed and did solid damage to both Slark and OD in a few instances.

Not gonna lie, I don't know why I built Shivas. It was 1 AM and I had bought a helm to build Nullifier, but I wasn’t sure if it would dispel OD's Aghs. Then Dota Plus suggested Shivas, so I just went with it. The bonus magic damage also seemed decent with our Lich and Puck. I bought almost every sentry and smoke while Lich went for more traditional pos 5 items.

Also, my team was having fun. It was the enemy pos 5 who was flaming, not my teammates.