INFINITE LOOP OF ATTACK
Method with the Watcher (the mantra lady, 4th and last character to be unlocked).
I'd like to point out that I don't watch Youtube nor other player’s channels nor have I looked up any guides on the net, so I'm extra proud to have come up with a method of my own, which also helped me to unlock at least 2 other tough achievements in this game using what I'm gonna describe right now.
You only need 3 cards (and two of them you already start with since the beginning of the game) and a relic called Violet Lotus, which gives you an additional energy point whenever you exit Calm.
The cards you are gonna need are:
- Eruption ("Deal 9 damage. Enter Wrath")
- Vigilance ("Enter Calm. Gain 8 Block")
- Rushdown ("Whenever you enter Wrath, draw 2 cards")
From the above, Rushdown is the one you are going to have to acquire along the way.
Using the three of them in the right order will make you enter an infinite loop of attacks until any enemy is dead. It works not only on bosses but it might help you defeat any foe such as the Transient or any other high HP enemy as well. The downside per se is that the damage done with each attack is small, so it will take many hits to end the fight, but it works great and that's what matters in the end. Here's the step by step:
1- First, play Rushdown to apply its effects on this turn/fight. 2- Then play Vigilance to enter Calm and 3- finally use Eruption to enter Wrath and attack. That's it. Rinse and repeat steps 2 and 3 to keep attacking.
Having those cards upgraded is a plus (or even a necessity in case you only have 3 total energy to spend, since Vigilance costs 2 and upgraded Eruption costs 1). When you exit Calm you earn 3 more energy, which is essencial for the loop since you will keep spending those earned energy points on Vigilance and Eruption, respectively, over and over.
You are also gonna need to have a hand of about 7 cards in total, because when the Rushdown effect happens you need it to bring back those 2 other cards that you are using to keep the loop and attack, that is, Vigilance and Eruption. If you have more than 7 cards total you risk breaking the loop in case one of those 2 doesn't return to your hand when redrawing.
In order to achieve only 7 cards or less in your hand, simply take advantage from the beginning of the game to get rid of the other ones you don't need. There are plenty of opportunities between some of the ? (question mark) events and also the removal services found in shops. For me it seems almost like the game notices that I'm playing this way (minimalist deck) from start and throw a lot of such opportunities.
I unlocked this achievement on my way to the final boss (before the Heart), on act 3, and I used this same technique that had worked on the Transient for the other achievement. Because I was learning as I went (used no guides), I had a few cards over the 7 total in my hand but I also had a Blasphemy card ("Retain. Enter Divinity. Die next turn. Exhaust.") and a potion which allowed me to enter either Calm or Wrath as backups. Those extras helped me get the loop started. So I first entered Divinity, then used the Rushdown card, then a potion to enter Wrath. By doing that, I was finally able to have Eruption and Vigilance in my hand to start the proper loop as explained. I was unlucky to get the toughest boss (in my opinion) as the enemy, the Awaked One, but as soon as I killed him the first time that other achievement unlocked.
About the Violet Lotus relic:
Although much on this game is random, there are certain patterns you can learn by experience or you could, for instance, read the wiki dedicated to this game. I've noticed thru experience that the Violet Lotus can appear at least from these 3 different events:
- At the beginning of the climb, (IF you have reached a boss on your previous attempt and) if you decide to swap your original relic (Pure Water) for it;
- Before the first boss (although I believe it could also appear after him, since the relic's order as a reward or acquirable item tend to change every time). I'm adding this just for reference, for it has happen to me multiple times and it could help a player trying the achievement for defeating a boss on turn 1.
- As a reward for defeating the 1st boss on chapter 1. This was what happened to me when I beated ascension level 20, although it might be worth to remember that it is NOT always shown as one of the 3 possible rewards, it doesn't happen often or at least every time.
EDIT: Qwanimal suggests, in case you can't find the Violet Lotus relic, players can use the Inner Peace ("If you are in Calm, draw 3 cards, otherwise Enter Calm") card instead of Vigilance since it allows players to enter Calm costing only 1 energy.