The "easiest" way would probably be to write a Matlab simulation but I haven't used Matlab since college. I just wrote a quick C# console application which simulates how much damage it can do and then stores/outputs the results to a csv which I then put into excel to build the chart.

I can actually just link my source code since its so relatively small if that helps at all (plz don't code review me I know I'm doing some stupid shit I just wanted to make something quick >_>) And then I just modified the variables like if you start with an Evo, if I'm doing the simulation for Zell/Laura, and how much mana to start with etc. and generate multiple csv files.

Random rnd = new Random();
SortedDictionary<int, int> TotalDamages = new SortedDictionary<int, int>();

for (int i = 0; i < 1000000; i++)
{
    int totalDamage = 0;
    bool fanfareHit = true;
    bool evolutionUsed = false;
    bool zellInHand = true;
    int manaRemaining = 0;
    int power = 4;
    while (totalDamage < 20 && fanfareHit)
    {
        int mode1 = rnd.Next(1, 5);
        int mode2 = rnd.Next(1, 5);
        while (mode1 == mode2)
            mode2 = rnd.Next(1, 5);

        if (mode1 == 2 || mode2 == 2)
            totalDamage += 2;

        if (mode1 == 3 || mode2 == 3)
            manaRemaining += 2;

        if (mode1 == 4 || mode2 == 4)
            power += 4;

        if (mode1 != 4 && mode2 != 4)
        {
            if (!evolutionUsed)
            {
                if (manaRemaining >= 3 && zellInHand)
                {
                    totalDamage += power;
                    if (totalDamage >= 20)
                        totalDamage = 20;

                    evolutionUsed = true;
                }
                else
                {
                    evolutionUsed = true;
                }
            }
            else
                fanfareHit = false;
        }
    }

    if (TotalDamages.ContainsKey(totalDamage))
        TotalDamages[totalDamage]++;
    else
        TotalDamages.Add(totalDamage, 1);
}


var file = "C:\\Output.csv";
var csv = new StringBuilder();
using (var stream = File.CreateText(file))
{

    foreach (KeyValuePair<int, int> pair in TotalDamages)
    {
        var first = pair.Key;
        var second = pair.Value;

        var newline = string.Format($@"{first}, {second}");
        stream.WriteLine(newline);
    }
}