Since you already took your time to make this forum post, I guess you won't mind a longer reply.
I agree with you that arena is tough. What I noticed is that opponents seem to be primarily selected depending on your account's power score. I think your account's level could also play a role, but not sure about it as to how much it matters. Your team power doesn't matter at all. Basically this means that if you keep all your champions in your vault and have them geared that you are more likely to find harder opponents.
You got fairly good champions for arena [High khatun (40) Warmaiden (40) Galek (50) and Miscreated Monster (60)]. Generally, your problems could be the following:
- You use the wrong champions, team composition or team lead.
- You have too low speed and/or their turn order is not correct.
- You have too low damage output and/or don't land your debuffs.
- You don't have enough good gear and/or use it incorrectly.
- You don't have your skill upgraded and/or your masteries unlocked.
- You attack the wrong teams/champions.
I'm really no expert on the topic, but let me try to give some insight that may help you with your journey.
(1) You got fairly good champions and decent good team composition, although I'm not entirely sure about Galek - he alright but not fantastic. Who is your team lead? Personally I go for a speed lead, because speed is key, especially if you have lower team power than your opponents. Keep in mind that an Aura only increases stats based on your champions' base stats, not they total stats. Let's say you had a 20% speed lead and your champion has 100+80 speed. The 20% only refers to the 100 base speed, not the 80 gear speed. So you end up with (100 * 1.2) + 80 = 200 instead of (100 + 80) * 1.2 = 216 speed. Thos is the case for any aura.
(2) Generally, it's really important to have the correct turn order and enough speed. If you use High Khatun as a speed lead, you will go first in more battles. If you have lower power score than your opponents and don't go first, you basically lost (unless you have S tier arena champions). Seeing your champions, you want your turn order as follows: High Khatun -> Warmaiden -> Galek or Miscreated Monster. In terms of speed, you want about 104 + 70 on your High Khatun. The higher, the better.
You also want to make sure that there is no (big) speed gap between her and your following champions. Otherwise, your opponent could get their speed boost going and attack you first. If I'm not mistaken, if you had High Khatun's speed aura and the following speed values
- High Khatun: (104 * 1.19) + 66 = 190
- Warmaiden: (97 * 1.19) + 60 = 175
Galek: (103 * 1.19) + 40 = 161 (Edit: actually 161 speed is enough, turn meter is a mysterious topic).
- Galek: (103 * 1.19) + 30 = 151
that the enemy could get a chance to take full control of the battle after Warmaiden took her turn. That is because High Khatun's 15% speed meter boost isn't enough to ensure that Galek takes his turn next. I'm not entirely sure how much more speed Galek would need in this example to go next for sure, but I hope you get the idea. Another edge case to keep in mind that it's possible that the aura messes your order up. This can be the case when a champion with low base speed and much speed gear doesn't receive a lot of speed from the aura.
- Champion A: 85 + 85 = 170. With 19% speed aura = 186 speed.
- Champion B: 107 + 60 = 167. With 19% speed aura = 187 speed.
That already happened to me and can be huge pain when you don't have the needed gear/glyphs to fix it. So keep that in mind.
(3) In terms of dealing damage, it's extremely important that your Warmaiden lands her decrease defense debuff! It massively increases your nukers' damage, so you want to make sure to have a minimum of 100 accuracy, preferably 150+. That should be more than enough to reach Silver. In terms of Warmaiden's masteries, you want go for the support tree and get Pinpoint Accuracy, Charged Focus and Swarm Smiter. These three masteries will effectively increase your accuracy by 10 + 20 + 16 = 46, which is huge! Also keep in mind that against weak affinity (Spirit), Warmaiden has the chance to score a weak hit and thus apply no debuffs. That's why she is most effective against Magic and Force champions. I think the chance of a weak hit to happen is 35%, so don't underestimate that!
The next thing to note is that you want 100% crit rate on your nukers and a balance between attack and crit damage. If you have 2.500 attack but 50% + 0% crit damage, then you will deal less damage than you could with, for example 2.000 attack and 50% + 50% crit damage. I don't know the specifics, but going full attack is not good, neither is full crit damage.
The last thing I want to say about this topic is that a single nuker could be more powerful than two nukers. That is the case when you use another support champion that casts additional buffs (like increase attack) or debuffs (like weaken). Also note that Miscreated Monster's damage is based on HP, so you won't be easily able to increase it. It's not affected by increase attack buffs. The good thing about that is that it's also not affected by decrease attack buffs.
(4) Another topic I want to mention is gear. You really want to make sure that you don't use gauntlets, chestplates or boots that have "flat stats", so no +1.000 HP, no +100 DEF, no +100 ATK. This is especially true for your nukers. It's not as important for your turn meter and debuff champion, since they rather need speed (and accuracy) over anything else.
Give Warmaiden as much Perception gear as possible, since it will increase her speed and accuracy, exactly what she needs. It's craftable in the Forge and even a solid 4* piece is more than enough. Accuracy and Speed set are also fine on her. Consider equipping her with a chestplate that has accuracy as main stat. Equip ALL your champions with speed boots. Even if you have to sacrify a 2-set combo, do it! The additional speed is what matters! There are a few exceptions to that, but most likely, they don't matter here.
Your Galek should have ATK% chestplate, crit rate % gauntlets and speed boots. Try to get enough crit rate from the other gear and the +5% from the offensive mastery Deadly Precision. If you somehow manage to get 100% crit rate without gauntlets, go for crit damage gauntlets. If you somehow manage to have high speed without speed boots, go for ATK% boots. I guess with Galek, you want 2.500+ damage and 150%+ crit damage. If it's only 2.000 damage and 100% crit damage it's also fine and probably enough to get you to silver, since the decrease damage debuff from Warmaiden is the most important part.
I'm not sure about Miscreated Monster, I don't have him. Probably give him high speed and HP gear. If you got a Shield set, consider giving it to him. He could keep your nukers alive for that one extra turn that you may need to win a battle.
A last note about gear is that your nukers won't be too useful outside of arena, since they are basically glass cannons and quickly die. If you also want to use them in dungeons, consider giving them a HP% chest, as that is advised in order to distract the enemy AI on targeting them. However, the lower damage could reduce your chance of winning arena battle though, you probably need to make a compromise.
(5) At first glance skill upgrades and masteries don't seem like a big deal, but they have a massive impact. In this case I mean the nukers, whose damage will be increased massively if they are fully booked and have the correct masteries. Galek's Hellraiser skill for example will deal an additional 25% damage if you fully book it. That is massive! Further damage can be gathered from Keen Strike (+10% crit damage), Heart of Glory (+5% damage), Bring it Down (+6% damage) and so on. I'm not sure about Shield Breaker. It sounds good on paper, but I heard some people say that it's not that great. I think Ruthless Ambush also doesn't work as most people think it does. Consider doing some research about masteries and watching a YouTube video may help too. Also, don't blindly copy suggested mastery trees from the internet!
(6) The last point I want to mention is the enemy teams and champions. First of all, you preferably attack enemy teams that have many weak affinity champions against your Warmaiden. In your case, you probably want to attack teams that have 2-3 champions of Magic affinity. Next you want to avoid enemy teams with low power score, a speed lead and Kael as a nuker. Chances are that they have 200+ speed and 1-hit kill you in the blink of an eye. I also would avoid teams with a (high) resistance lead, since it could mean your Warmaiden won't hit her debuffs. However, if she has the accuracy masteries and 150+ accuracy, there usually isn't a problem attacking teams with resistance lead, at least in Bronze and Silver. Another thing is that enemy teams with high team power usually have rather high resistance and health and fairly low speed. At least, that's my experience in Bronze and Silver. Apparently, since my current speed lead Gorgorab has bad gear, I prefer to attack opponents with higher power score than mine, since it increases the chances for me to go first.
In the battle, you obviously have your general routine of: Increase turn meter -> debuff enemy -> nuke them. If any opponent survives, you should consider attacking the reviver first. However, if the opponent's nuker is about to attack, better target it first, especially if it has damage buff... it really depends on the situation. You will figure these things out on your own. There are also a few champions that you want to avoid fighting, such as Skullcrown, Madame Serris, Duchess Lilitu and so on. It takes a while to know which teams are easy and which ones are hard to fight, but you'll learn it after a while.
I hope this helps.
If any of my information or thought process is questionable or wrong, simply point it out.