Since Plarium doesn't seem to have published the reward tiers, I thought I'd post what we've unlocked so far so people have an idea what they're in for if they want to get the holy bonds from the new tournament.  

Keep in mind the weighted average of the pumpkin drops is 1.08, so that means over a large number of champion sends you'll get roughly 1 pumpkin per send.  

Lvl 1 = 1 Pumpkins (100 Energy)  [total=1]

Lvl 2 = 3 Pumpkns (4 hr Champ XP Boost Item) [total=4]

Lvl 3 = 8 Pumpkins (Epic Bond) [total=12]

Lvl 4 = 15 Pumpins (7 Day Hunt Activator) [total=27]

Lvl 5 = 30 Pumpkins (4 Hydra) [total=57]

Lvl 6 = 4 Pumpkins (Tier III Orb) [total=61]

Lvl 7 = 35 Pumpkins (10 Emeralds) [total=96]

Lvl 8 = 55 Pumpkins (2 Fallen) [total=151]

Lvl 9 - 80 Pumpkins (x2 Tier IIi Orbs) [total=231]

Lvl 10 = 120 Pumpkins (150 emeralds) [total=351]

Lvl 11 = 8 Pumkins (Tier IV Orb) [total=359]

Lvl 12 = 165 Pumpkins (1000 Energy) [total=524]

Lvl 13 = 226 Pumkins (200 Emeralds) [total=750]

Lvl 14 = 305 Pumpkins (x4 Epics) [total=1055]

Lvl 15 - 410 Pumpkins (x2 Tier IV Orbs) [total=1465]

Lvl 16 - 20 Pumpkins (300 Energy) [total=1485]

Lvl 17 - 555 Pumpkins (300 Emeralds) [total=2040]

Lvl 18 - 745 Pumpkins (x3 Tier IV Orbs) [total=2785]

Lvl 19 - 1005 Pumpkins (400 Emeralds) [total=3790]

Lvl 20 - 100 Pumpkins (1200 Energy) [total=3890]

Lvl 21 - 1350 Pumpkins (x2 Tier V Orbs) [total=5240]

Lvl 22 - 1810 Pumpkins (x3 Holy Bonds) [total=7050]

We don't know how many more levels there are before you reach the holy bonds, but you're looking at a minimum of about 7,000 sends.  A hunt item does 120 sends per hour, so you'd have to keep it running (refreshing champions ever hour or so) for around 58 hours over the course of the 3 day event.  The special package with 400 recharges for $10 is recommended for anybody attempting to do this as without it you'll end up going through a whole lot of emeralds, but the time commitment is also going to be quite large.