It's a Beast Boost building
I'll get some info up but it seems to be a lot like the nomadic traders
Unmodded costs
1. 25,000
2. 32,500
3. 45,500
4. 68,250
5. 109,200
6. 185,640
7. 393,114
8. 825,537
9. 1,811,980
10. 4,177,215
Unmodded times
1. 24
2. 27
3. 39
4. 47
5. 55
6. 63
7. 71
8. 79
9. 87
10. 95
Listed building effect (maybe)
1. 6% more attack and defense from beast
2. 8% more attack and defense from beast
3. 10% ""
4. 13% ""
5. 16% ""
6. 20% ""
7. 25% ""
8. 30% ""
9. 35% ""
10. 40% ""