Before the battle with Grimm, it is advisable to be fully armed. That is, to have 11 slots of amulets (during the passage of DLS 2 slots will have to be spent on the Gloomy Child amulet)
Shadow cape.
Necessarily a clean nail, otherwise the battle will simply endless.
Well, you need more masks, because in one attack the boss deals as much as 2 damage.
Having the necessary amulets is extremely important.
To begin with, I recommend practicing using amulets such as: Fragile Heart, Lifeblood Core and Joni's Blessing






So, playing without restarts, you will quickly remember Grimm's attacks and practice dodging them.

Lunge
With this attack, Grimm lunges, takes off and spews out clots of flame throughout the location. As for me, the simplest attack is just enough to dash towards Grimm and move away a little, controlling the fall of the bunches

Lunge from the air with a trail of fire
The name speaks for itself. For me, it was the most difficult attack, because I always wanted to make a dash in his direction, which cannot be done because of the fiery trail. You need to jump and go sideways with the help of wings / breathing . Particularly dexterous, you can manage to hit Grimm from above.

Grimm releases 4 bats from his sleeves
Casting this attack for quite a long time, run in his direction, after the first mouse flies overhead, make a middle jump + dash . Then you can inflict 1-2 blows.

Spikes
Thorns appear all over the map. just try not to get hit by them . Here is a window for heal, you can replenish one mask (even without fast focus).

Pillars of flame
Grimm hovers in the air and releases pillars of flame from the ground in the place where the character is. We go in the direction of Grimm and inflict 1-2, or even 3 blows on him, if the pillars are clamped against the wall, then we just move a little to the side and make a dash in the opposite . Do not forget that there is a clot in place of the pillar for some time, which can cause damage.

Ball
Grimm turns into a large ball and releases small balls of flame. With this attack, it is important to keep the balance in the jump height - hold down the button a little less / longer - received 2 damage, it is also important not to stand still, but to move, slightly approaching and moving away from Grimm. Grimm makes this attack at 75/50/25% health.
IMPORTANT: After this attack, inflicting 2-3 blows on Grimm, he will turn into a bat, which can be hit several times or restore up to 3 masks (without fast focus)

I used a build like this:








- Sharp Shadow
In the battle with Grimm, you will often have to use dash, so this amulet is just a must-have, since we can inflict damage on him, so also a dash further.



- Dashmaster
In this case, it just perfectly combines with the shadow due to the increased damage from the dash. In total, for one dash through Grimm, it will turn out to inflict 50% more damage from the current level of the nail. (With a clean nail it is 31.5 damage)


- Strength
An additional 50% damage from a nail, what else do you need?



- for those who like to play through the nail techniques, you can replace the fragile heart with the halo of the nail master and the song of the caterpillars just for additional souls, so that if something happens, heal on the attack with thorns or use a long nail ↓↓↓↓↓

- sometimes, during attacks with bats and levitation, I would like to have a longer range of the nail - this amulet solves the problem.

It took me about an hour to complete, tried different builds, but this one turned out to be the most effective for me, I wish everyone good luck!