82,000 points for all rewards => 2,734 points per person (30-person guild)
Looks like it is reachable without any Shop Tier buys: 60-64 battles can hit the mark with luck.
You could try Tier 0 and If your luck turns out bad, buy Tier 1 later.
Note: Assuming you can manage without the badge/medals from Shop tiers.
It should be noted that the score range is insanely high (2nd image below):
- 54 battles - 2,832 points
- 54 battles - 1,864 points
Initial thoughts and guesstimate
p/s The closest precedent to this scoring method is Stag Party (Aug 10)
Scale Assassin: 1 Antidote = 23.6 pts on average, 40 pts max(?)
Mist Assassin: 1 Antidote = 23.6 pts on average, 40 pts max(?)
(Epic) Kobra: 4 Treasures = 16 pts to start, then 20, 24, 28, 32, 36, 40…
(Legendary) Viper: 4 Treasures = 16 pts to start, then 20, 24…
(Mythic) Euryali: 2 Antidotes = 47.2 pts on average, 80 pts max(?)
(Mythic) Mambasira: 8 Treasures = 32 pts to start, then 40, 48, 56, 64, 72, 80…
By the 3rd Kobra/Viper battle, they are worth more than the Assassins (on average).
By the 7th Kobra/Viper battle, they are worth equal to or more than the Assassins can ever be (assuming 1x, 1.4x, 2x multipliers).
Same considerations between Mambasira and Euryali (both @ 2x the above comparison).
Even at 60 battles (~12 of each non-Mythic battle) minimum from 28 free sigils and valravens, the tipping point is very early to prefer scaling Treasures to RNG Antidotes.
However, this information is moot if the available battles have been randomly chosen but thereafter locked into a pseudo-preset script, which means the battles are more than likely to be Scale>Mist>Kobra>Viper>Euryali>Scale>Mist>Kobra>Viper>Mambasira and repeating thereafter with guided quasi-equality in number of battles. Such a progression hints at a guesstimate range of points by shop tier
Shop Tier (total battles -- *edited: left in a 5x multiplier from last event*)
0 (60-64): 1969 - 2136 points
1 (64-68): 2136 - 2290 points
2 (70-74): 2431 - 2612 points << guessing ~78,000 total required
3 (80-84): 2930 - 3127 points
4 (90-96): 3467 - 3747 points
EDIT post go-live: In retrospect, the average points for Euryali ends up higher than 1.18x due to the 1.4 multiplier causing 2.8 antidotes to count as 3 antidotes, pushing the average up a little. The better news is that player choice (of battle) seems to play a big role this week, and actually makes a difference.
Take the highest rarity battle always.