How many different decks with mana costs equal to 20 are currently possible? I wrote a small python script to answer this question. I did the following steps:

• read all cards from https://steemmonsters.com/cards/get_details
• build a card dictionary by the card id
• creating a list with all possible color combinations
• Then I build sets with possible card combinations that summing up to mana costs equal to 20

Conditions

• A set starts always with a summoner
• Only 1 summoner is allowed
• Each card can exist only once in a deck
• All cards have their maximum level
• Mana cost must exactly be 20
• Gray cards can be used with each color
• A Gold summoner can pick one additional color + Gray

The Gold cards are special, as they can be combined with another color. So I created a unique name, e.g. "Gold_Red" for this.

All colors can be combined with Gray cards. "Red" means the combination of "Red" and "Gray" cards. I added also "Pure_Red" which excludes the use of "Gray" cards.

Results

Results ordered by different colors

color	card combinations with mana=20
Red	2478
Blue	2304
Green	1787
Black	3444
White	2181
Gold	77
Pure_Red	79
Pure_Blue	81
Pure_Green	64
Pure_Black	98
Pure_White	79
Pure_Gold	1
Gold_Red	1298
Gold_Blue	1198
Gold_Green	936
Gold_Black	1805
Gold_White	1126
Pure_Gold_Red	71
Pure_Gold_Blue	69
Pure_Gold_Green	53
Pure_Gold_Black	98
Pure_Gold_White	66

Results ordered by different summoners

summoner	card combinations with mana=20
Malric Inferno	1070
Alric Stormbringer	994
Lyanna Natura	770
Tyrus Paladium	936
Zintar Mortalis	1494
Selenia Sky	6055
Talia Firestorm	1408
Xia Seachan	1310
Xander Foxwood	1017
Kiara Lightbringer	1245
Jarlax the Undead	1950

Conclusion

The new Gray cards increase the number of deck combination a lot. Selenia Sky is the summoner with the highest number of card combinations, whereas Lyanna Natura has the lowest number of card combinations.

The new summoner from the beta release increases the number of card combinations, as their mana cost is reduced by 1.

The Black cards have the highest number of card combinations and Green cards have the lowest number of card combinations.

Source code

import requests
import itertools

if __name__ == "__main__":
       
    response = requests.get("https://steemmonsters.com/cards/get_details")
    cards = {}
    for r in response.json():
        cards[r["id"]] = r
    colors = {"Red": ["Red", "Gray"], "Blue": ["Blue", "Gray"], "Green": ["Green", "Gray"],
              "Black": ["Black", "Gray"], "White": ["White", "Gray"], "Gold": ["Gold", "Gray"],
              "Pure_Red": ["Red"], "Pure_Blue": ["Blue"], "Pure_Green": ["Green"],
              "Pure_Black": ["Black"], "Pure_White": ["White"], "Pure_Gold": ["Gold"],              
              "Gold_Red": ["Gold", "Red", "Gray"], "Gold_Blue": ["Gold", "Blue", "Gray"],
              "Gold_Green": ["Gold", "Green", "Gray"], "Gold_Black": ["Gold", "Black", "Gray"], 
              "Gold_White": ["Gold", "White", "Gray"],
              "Pure_Gold_Red": ["Gold", "Red"], "Pure_Gold_Blue": ["Gold", "Blue"],
              "Pure_Gold_Green": ["Gold", "Green"], "Pure_Gold_Black": ["Gold", "Black"], 
              "Pure_Gold_White": ["Gold", "White"]}
    
    min_mana = 20
    max_mana = 20
    level = -1

    all_summoner_list = []
    all_monster_list = []
    
    for r in cards:
        if cards[r]["type"] == "Monster":
            all_monster_list.append(r)
        else:
            all_summoner_list.append(r)
                    
    color_sets = {}
    for color in colors:
        print("Calculating combinations for %s" % (color))
        summoner_list = []
        monster_list = []
        
        for r in cards:
            if cards[r]["color"] not in colors[color]:
                continue
            if cards[r]["type"] == "Monster":
                monster_list.append(r)
            elif cards[r]["color"] == colors[color][0]:
                summoner_list.append(r)
        sets = []

        for k in summoner_list:
            for L in range(0, len(monster_list)+1):
                for subset in itertools.combinations(monster_list, L):
                    mana = 0
                    mana += cards[k]["stats"]["mana"]
                    for s in subset:
                        mana += cards[s]["stats"]["mana"][level]
                    new_set = set((k,) + subset)
                    if mana <= max_mana and mana >= min_mana:
                        if new_set not in sets:
                            sets.append(new_set)
        color_sets[color] = sets
    
    summoner_sets = {}
    for summoner in all_summoner_list:
        for c in color_sets:
            for s in color_sets[c]:
                if summoner not in s:
                    continue
                if summoner not in summoner_sets:
                    summoner_sets[summoner] = [s]
                elif s not in summoner_sets[summoner]:
                    summoner_sets[summoner].append(s)
    
    print("| color | card combinations with mana=20 |")
    print("| --- | --- |")
    for color in colors:
        print("| %s | %d |" % (color, len(color_sets[color])))
    
    print("| summoner | card combinations with mana=20 |")
    print("| --- | --- |")
    for s in summoner_sets:
        print("| %s | %d |" % (cards[s]["name"], len(summoner_sets[s])))

---

update: I did a small mistake in the script. The results are now corrected.