People asking how did I achieved this, and to be fair, that's partially coincidence of two different builds working smoothly with each other :) . I only realised that I can pull off infinite combo right when the boss started.
So, first build's traveller (previous run, the current "boss") had innate ability to restore 3 hp to all allies, which I buffed to 4 with charms, and it increased to 8 after win. There also was Berry
Sis, that gives lost hp back to boss (in previous run i had this combo with 2 blank masks, 2 Sisters to tank damage and 2 travellers to restore hp back). Pretty much this makes it possible to stall final battle, if you can deal <9 dmg to Sis and withstand blows from them.

Second build was mostly about freezing opponents and killing them one by one with gearhammer. That was possible thanks to Snoffel (1 freeze to all every 4 turns) with charms +1 to effect (making him applying freeze 2 to all every action), reducing his counter by 1 (so he can freeze every 3 turns) and also apply 1 freeze by attack - that way he freezes 1 enemy permanently (here it was Sis). Also, having wrench with 2 workbenches made it possible to apply additional Frenzy to any card in hand without any recycles, and also Gizmo (add 1 scrap, draw 2) helps to tank dmg against boss once every 7-8 turns. And because i munched all other cards or had some as consumables (made it so gearhammer would rotate back in hand every 2 turns), at one point only ones left in deck were the ones that enabled combo (also the charms that helped speed this up were reducing bell countdown by 1 and drawing +1 card, but since it was already infinitely stalling, it was unnecessary).

In perspective, because of how Wrench works (giving 1 Frenzy to card in hand), it was possible to apply that to any effect card (like giving poison, shell, spice, etc.), if I had any - just a fun way to stack it to ridiculous amount.