The third way, is to use SDD squad.
You may want to bring a Kane grand ranger as well (if you have sufficiently built his critical), otherwise, you may want to bring a Darrion or Faye holy defender, or even Altima Holy Defender if you have one. If you bring Kane or Altima, be sure to put him/her inside both the lifesteal and matilda Witch Doctor aura for little chance of refresh. If you have a Rheia Gladiator, you can also put her in, as she's quite easy to refresh and may/can stun up to 3 enemies while under Celestial Form effect.
With SDD you should be able to plow through the two enemies in front of Kristoff quite easily in a single turn. Just make sure you keep a refreshed Drake/Leon before killing the last of the two, so you can immediately march forward. By doing this, Rin will try to catch up with your squad.
Try killing Kristoff before Rin able to approach. If she comes too close, please try to disable her anyway you can before she can attack. It's because her attack cause 2-3 turns blind. She should close in on your party on third turn if you managed to kill the two enemies in front of Kristoff in one turn, on which turn, your Rheia Gladiator will have her Celestial Form ready. Cast it, and have Matilda and/or the lifesteal hero attack to refresh Rheia. Once she's refreshed, attack Rin and pray that the on-attack effect kick in. Otherwise, Try stunning her with Kane. If unable to disable her, just pray she doesn't hit your main damage dealer.
Once you kill Kristoff, you can have your team turn around and kill Rin.
Why you'd want to prioritize killing Kristoff? His active skill cause aura disable.
After killing Rin, it should be quite easy to deal with the remaining archers.
At the beginning of boss wave, you'd want to summon Matilda's pet in front of the mobs on the back (right side of screen). Her pet will serve as diversion while you try to kill enemies right in front you. You'd want to pop your guardian skill at this point (if available). Also, you might want to have Kahuna use his heal on Matilda's pet, just to increase its' survivability and deal some amount of damage to enemies at the back.
If you bring Gladiator, Rhea, she can go deal with the enemies on the back, if not to only sufficiently disable them. The same goes with Kane Grand Ranger or Altima Holy defender.
The rest of things, it's basically praying your Drake/Leon has enough dps or trigger to outright kill Sylvia, then proceed to the two thieves and two healers. After you are done with the left side, switch to the right side (or what left of it if you bring Gladiator Rhea).
If your drake is unable to kill Kristoff on time before Rin is able to attack, or if you don't have sufficiently built archers (to reliably critical hitting most of the time and to follow whodahackii's guide), then I'm sorry to say this, but I think you are not yet ready to tackle Master.
And I mentioned Leon there, but bring him only if you have built him properly. Otherwise, bring Drake instead.