Who is the construct again? The guardian from act 1 or the automaton from act 2?

Either way, it's been a while but here's what I used to focus on:

For the guardian, you sometimes need to take a few risks when taking gems on your way to the next rest site. This allows you to either have a small deck of powerful standalone cards, accumulate more tools to stack and retain block, scale thorns, or make temporary strength/dexterity permanent. Make sure that fights don't take too long since "curling up" gets more expensive each time it wears off.

For the automaton, this is one of the few characters who intensely benefits from deliberately keeping your deck small. There's even an argument for eventually removing the basic attack that returns after encoding because you don't want to draw it in long fights.
Instead, especially before the final battle, make sure that you can work towards one set of powerful purple cards, most of which you play each turn to win by virtue of raw efficiency. Any leftovers can be "pseudo-exhausted" by adding them to an unfinished function.

As far as I remember, there was also a 2-cost power that automatically exhausts the first status/curse you draw each turn. That one helps a lot in act 4.

Originally posted by Zu:

Who is the construct again? The guardian from act 1 or the automaton from act 2?

Either way, it's been a while but here's what I used to focus on:

For the guardian, you sometimes need to take a few risks when taking gems on your way to the next rest site. This allows you to either have a small deck of powerful standalone cards, accumulate more tools to stack and retain block, scale thorns, or make temporary strength/dexterity permanent. Make sure that fights don't take too long since "curling up" gets more expensive each time it wears off.

For the automaton, this is one of the few characters who intensely benefits from deliberately keeping your deck small. There's even an argument for eventually removing the basic attack that returns after encoding because you don't want to draw it in long fights.
Instead, especially before the final battle, make sure that you can work towards one set of powerful purple cards, most of which you play each turn to win by virtue of raw efficiency. Any leftovers can be "pseudo-exhausted" by adding them to an unfinished function.

As far as I remember, there was also a 2-cost power that automatically exhausts the first status/curse you draw each turn. That one helps a lot in act 4.

I'm talking about the guardian, sorry.
I think I'm going to give up on this one, I've been trying a bunch of times, but I can't beat the final boss.

Ok, I played a guardian run to refamiliarize myself with the mechanics.

Really it's all about stacking strength and dexterity either by lowering the debuff of temporary stats or negating them entirely with artifact.
You achieve this by strategically placing gems on cheap cards, ideally with multiple sockets.
In order to benefit from these interactions more consistently, use stasis as a form of retain and accelerate for tempo.
Thorns help but they can't solve act 4 by themselves.
Brace helps you prepare for key turns but (again) 50 brace is a tall order.

In short:
All mechanics contribute but strength + vulnerable + multi hit attacks are what kill act 4.

Originally posted by Zu:

Ok, I played a guardian run to refamiliarize myself with the mechanics.

Really it's all about stacking strength and dexterity either by lowering the debuff of temporary stats or negating them entirely with artifact.
You achieve this by strategically placing gems on cheap cards, ideally with multiple sockets.
In order to benefit from these interactions more consistently, use stasis as a form of retain and accelerate for tempo.
Thorns help but they can't solve act 4 by themselves.
Brace helps you prepare for key turns but (again) 50 brace is a tall order.

In short:
All mechanics contribute but strength + vulnerable + multi hit attacks are what kill act 4.

It's true, but for having played a bunch of times; these cards are actually pretty rare.
A lot revolves around stasis and gems, and I didn't find these mechanics particularly helpful end game.
This character suffers a lot from attrition and there are very little ways to mitigate that.