Leviathan + Dagger vs Leviathan + Dagger = Unbalanced combat

While I agree CG made a huge mistake with this, mirror matches are pretty easy and consistent even if the opponent goes first if you use Tie Reaper as first reinforcement for its turn meter removal as it effectively resets the coin flip. 

People lose because they'd rather moan than google what is now a couple of weeks old solution.

You're still ultimately at the mercy of a coin flip - and SOMETIMES if you stick with it and slug it out to the end you can still pull it out if you lose the second coinflip - but it doesn't change that the matchup is objectively worse than before they buffed dagger. And now there are fewer Levi counters and there will be GAC matches that are lost to a coin flip - not skill - just pure RNG - you lose. This is not the kind of meta we want - it's not good for the game.

I think people SHOULD complain about this, even if there is a "sometimes it works" strategy in play. It's a much bigger goal post move than the new update is but everyone's busy freaking out about that. 

When the second move, the enemy Leviathan blows the hangars, the caused by Tie Reaper will be destroyed after the call. Good tactics when playing from 2 strokes.

This. If I go first, I can safely put it on auto for the most part, the only time I play manually is when my Mk6 shows up so I can use its nuke ability instead of having the AI focus on the specials. As for going second, I've tried the Reaper thing, and it's still a coinf-flip as to which Levi goes first. One battle, I used Reaper, both Levis were then tied in terms of TM, my Levi went first the following two turns, the enemy Levi went first when it came to Ult, which ended up costing me the battle, especially since each time a reinforcement shows up after that two of my ships are stunned, and when the enemy Mk6 shows up it immediately nukes one of my ships, whereas before the "rework" it was 50/50 whether it used its nuke basic or focusing on its special abilities.

I've said it several times already, with previous mirrors going first gave you an advantage, but even if you sent second you could and still can turn things around and win. With Levi, this is reduced significantly, the most you can do is get rid of the Bomber, and if you're in GAC hope you can clean up after that.

Reaper's reinforce ability will still fire before it's destroyed - so it still resets the enemy Levi TM to be equal with yours again - so every cap ship turn after that is technically a coin flip to see who goes - but the only one that matters is the coin flip for ult. 

It's not ideal. It's a workable strategy but still much worse than before. 

I thoroughly dislike the changes, but my track record is near 100% win rate using Reaper as first reinforcement.
As you say Reaper just reset the coinflip and it's much easier to pull the win if you go first on each of the following turns, however even if you lose the initial coinflip and all 3 flips after you've brought in Reaper, you can still win consistently, albeit timeout and edge cases pushes down on the win rate somewhat if all flips goes against you.

I hear people saying this and maybe I'm just playing the battle 'wrong' but what you're describing has not been my experience. I've heard one other person say they're approaching a 90% win rate - everyone else is saying 75-80%. So while you might be getting near 100%, I'm really comfortable saying you're an outlier.

I'd be happy to give a write up as I've seen a few different approaches to the mirror. And the below post is going to be super long, apologies in advance, but it's a stupid battle so need a lot of typing.....

Assuming the initial conflip goes against us, use dagger basic, always. Whenever possible, target Fury (Dagger have a bunch of turns where it can ignore taunt).
Use your bomber AoE first move, use Fury swarm on first turn, heal second. Use swarm whenever possible as long as most of your ships aren't dazed. Use bomber AoE as often as possible as well.
First Levi turn, use 2nd special, Second Levi turn, call in reaper to reset TM and initiate coin flip sequence.
First Levi turn after reaper always use sabotage hangars, if you go first their sith figther dies, if you go second, this ability does nothing really, but needs to be played. Heal up whoever needs it most.
Second Levi turn after reaper they can only basic, you call in MK6 and nuke their Bomber. Always nuke bomber in my experience, I see some suggest Dagger but that have never worked well for me.
Now, finally 1 ship is down, it's time to go all in on enemy Fury. Burn it down as fast as possible, user your own Fury to swarm, Bomber AoE, Dagger can either basic or AoE (yes, only now, once enemy Bomber is dead is it safe to use Dagger AoE).

A few different things can happen here, if you win the ult flip, it's easy. Assuming you don't there are two different situations you can find yourself in. Either enemy Sith Fighter is there if enemy won first flip after Reaper or you won that flip and enemy Sith Fighter died to sabotage hangars. Both these scenarios can be won, but it's obviously easier if you don't have to deal with Sith Fighter.
Anyway there are two relevant notes I've found, my preferred kill order is:
Bomber - nuke with your MK6
Fury - kill this one as soon as possible after bomber is out, assuming you got a little lucky with Dagger going around taunt it might be well damaged when bomber is nuked.
Sith Fighter - if it's present, kill it next
Reinforcements/Dagger - I'm not sure I have a fixed approach here, it depends a bit on who is called in and what health status is from other ships. Sometimes Scimitar enters the fray and forces your hand somewhat.
MK6 - killed last, mostly, see next wall of text. It's easier to kill MK6 when it does not have allies.

Now the final note is on how I deal with enemy MK6. Once it enters it will have 80 stacks, first turn it will try to nuke one of your ships. Best case it targets your own MK6, that causes enemy to drop 40 stacks and do nothing. Mostly though it nukes one of your ships.
If you were lucky and have taken out Bomber + enemy Sith Fighter died to sabotage Hangars, then you can target Dagger and allow enemy MK6 to climb above 40 stacks again. Try to get it to exactly 42 stacks while hitting on Dagger.
If above 40 stacks enemy MK6 will nuke again, if it's at 42 it dies to a single hit after nuke, which can be ideal case for you if enemy dagger is low on health and you're not left with only your own MK6 after a nuke.
Allowing enemy MK6 two nuke shots is .... interesting.... but it can shorten the battle considerably.

However if enemy MK6 nuke e.g. Bomber or Fury on your side, and they have Sith Fighter, Dagger and Bomber still, keep it below 40 stacks while following kill order above. You can still win this scenario, but mostly if this is where you land it's a mad race against the clock.
I've had several wins with less than 10 seconds to go, so yeah, I hate this fleet change despite my good win rate.

I'm happy to try and record a couple of videos if it's of any interest.

I'd be interested in a video - I think that would be helpful for a lot of people, and thanks for the writeup. 

Just did a mirror for fleet climb.
I had good rng on both first flip after Reaper as well as on enemy MK6 trying to nuke mine, so super easy win, but should still give some idea about my approach.

I would also add that whomever say this mirror isn't high win rate, I think if you isolate the battles with every coinflip lost and bad rng on who enemy MK6 target, that win rate isn't great. But those battles are not the majority since it requires a lot of rng to go against you.
https://youtu.be/UeAzfvJ3Qe4?si=idxfFu8BopCM3fNU