The Before Wine is Cooled into Azure Dragon's Ascension combo has a little too much synergy most enemies you would want to hit with it ( rank 3/ 4 ) would usually go before Martial Saint on turn one but then are almost certain to go after him on turn two which evens out the turn used on the set up rather brilliantly though since losing a turn is not a factor it can't be factored into the balance of the move which if used from the optimal position has a crit value of 49% ( 20% from position 4 + 20% from mark + 9% base crit) which is then paired with a damage output that far outpaces other back-line targeting attacks ( front-line damage into the back usually has a +0% damage mod in the base game roster unless it's Holy Lance against the undead which ends up as +35% at max rank) with the hit on position 3 reaching +35% and position 4 reaching 45% effective against all back-line enemies.

This by itself might not be enough to warrant looking into the combo but Azure Dragon's Ascension has an on kill buff making the almost certain kill on frail back-line enemies grant a notable advantage for the rest of the current leading into the next combat making this be the only opening you would ever want him to use.

This is of course not factoring in trinkets even among just his own ones the combo picks up some huge buffs with Hot Wine not only increasing the odds of the crit but also applies its own on kill buff to the rest of the party, Red Hare's spd increase removes the need for the debuff portion of Before Wine is Cooled from needing to stick and while it does provide a damage penalty it is effectively removed by the mark damage buff which then lets the Martial Saint an easy way to trigger the extra turn letting him either set up for the next round or finish off a low health enemy ( i'm going to assume there is a once per round cap on the extra action trigger.), lastly Mystic Dragon Blade would give it armour piercing all the while having it's damage penalty once again nullified by the mark damage boost which would give an effective damage mod of 25% against rank 3 and 35% against rank 4 while ignoring protection.

As far as theming goes the combo is incredible, cutting down a foe with a single well aimed strike is perfect though with the on kill effect of not just Azure Dragon's Ascension but the one's of his trinkets having it need relatively little help to have a certain kill on most back-line units.

For the Before the Wine is Cooled into Azure Dragon's Ascension combo, it was almost a design requirement because of how reminiscent it is of when Guan Yu killed Hua Xiong. However, compared to it is true that Forward 3 is harder to workaround when compared to Forward 1 on Holy Lance. In addition to these, he surprisingly lacks DMG when CRIT does not land (which was a result from beta testing), so I think this warrants some heavy DMG and on-kill buffs.

This is without mentioning that backline heavy hitters usually come with better supports than Martial Saint. Crusader and Arbalest has healing, Houndmaster has broken dodge tanking, stress heal, and the best mark in vanilla. Of course Martial Saint has his own backline support (Towering Presence with AoE stress heal), but from my experience of testing, I felt like this comes short when compared to vanilla heroes' support ability.

As for trinkets, I do agree that Red Hare can be too strong. However, the trinket almost nullifies all strength he has when it comes to first round strike strategy (which is commonly referred to as Alpha Strike in modding community), tanking his vs Rank 4 Ascension to maximum 18 DMG in level 5 (which is nowhere near enough to kill NG+ Pelagic Shaman even with CRIT). Its effect mainly kicks in starting round 2, but by then, his actions are good for mainly buffs (which are best used in round 1). Unless you combine trinkets to make it significantly stronger, my verdict on Red Hare is that it is not as strong as it is flashy.

Mystic Dragon Blade is strong indeed, but I think CoM trinkets deserve to have that power level.

Those being said, I think Ascension can use a little bit of ACC nerf. I'll talk to the project lead when it's possible. I think its being so strong comes from the fact that it has extremely high ACC.