Note: I will be talking about the bosses and their stats a bit in this thread so if you don't wanna spoil them for yourself you probably shouldn't continue reading this.
These tips are just some things I wrote down while playing through the game and fighting the first few bosses. They won't guarantee a win but with some good RNG and a little bit of luck they can help make the fights a little easier.
Boss #1: The Skeleton General
(HP: 400 ATK: 60 DEF: 10 Shield: 50 Crit Rate: 10% Dodge Rate: 10%)
Upon reaching Floor 10 the first few times you might have some difficulty passing this boss fight with your starting set of skills. As most of them deal too little low damage and take some turns to recharge, you will most likely lose the battle of attrition.
My recommended setup for beating this boss is with a high damage skill (Nightmare), at least two heal/shield skills (Spellbinding Circle, Magic Barrier, Orb of Life) to buy some extra turns while you wait for your main damage dealer to recharge, and low CD skills (Quick Hit, Darkness Tentacles) to chip away at the initial shield and waste dodge chances (see note 2).
Quick Hit has a high enough crit rate that it can reliably damage the boss every other turn.
Darkness Tentacles deals a little more damage than a non-crit Quick Hit while having an additional stun chance (albeit incredibly low) which could help tip the scales in your favour.
Boss #2: The Corrupted Druid
(HP: 800 ATK: 140 DEF: 10 Shield: 75 Crit Rate: 20% Poison Chance: 10%)
Dealing with this boss will be much more difficult as they can poison you. Poison damage ignores both your DEF stat and shield which reduces shield skills' effectiveness in this battle.
High attack damage skills might seem like a good choice as this boss cannot dodge attacks, but their long cooldown times mean you will probably eat a lot of poison damage before you get to use them again.
Your best bet is with good healing skills, a debuff removal skill, and both burn damage and poison damage skills.
Orb of Life, Spellbinding Circle, and Vampire Fangs can offer some healing.
Hamsa is a must-have as it can remove poison and burn effects.
Venom Splash does decent poison damage over 6 turns.
Both Earthquake and Fire Wave can dish out painful fire damage over 3 turns. Earthquake does way more damage while having a low chance to trigger and a high CD (5 turns), while Fire Wave deals less damage but has a higher trigger chance and a lower CD (2 turns).
Having both poison and fire damage means that both can trigger in the same turn, dealing more damage per turn than if you stacked only poison or fire alone.
Boss #3: Elizabeth
(HP: 1400 ATK: 240 DEF: 15 Shield: 100 Crit Rate: 10% Dodge Rate: 10% Stun Chance: 20%)
For this battle the boss has a 20% stun chance, which means you can be stun-locked for a number of turns, making normal damage attacks unreliable as your skills' CD timer will not go down if you are stunned.
As with the previous boss you will need to rely on poison and fire damage skills as they can still hurt your opponent even when you are stunned.
Heart Necklace is a very good healing skill at this stage as it restores a lot of HP while also giving a decent amount of shield.
Venom Splash still is the best skill for poison.
Earthquake and Fire Wave will do the job for fire damage.
Since the boss cannot burn or poison you in this battle you should replace Hamsa with another damage or healing skill.
Additional Notes:
1. Room Modifiers: Different room modifiers can greatly influence how the battle goes.
Damage (DMG+, DMG++, DMG+++) modifiers are the worst as they greatly reduce the number of turns you have to beat the boss depending on your DEF.
Room Poison (-10 HP per turn for you and your enemy) and Darkness Essence (-20 HP for you only) modifiers are scary early on but are more manageable with good heal skills.
Health Point (HP+, HP++, HP+++) modifiers make the fight last much longer so make sure your healing and shield skills can keep up with the continuous damage.
Stronger Enemies and Weaker Enemies modifiers change both the attack and health of your opponent by +50% and -50% respectively. Although for Boss rooms the Weaker Enemies modifier is usually much rarer.
The Chained Skill modifier locks one of your skill slots at random, which can ruin your build if it locks an important skill.
The Cooldown +1 modifier makes your skills take one turn longer to recharge, while the Cooldown -1 modifier makes them recharge a turn faster (they have no effect on skills that recharge in 1 turn). Similar to the Stronger Enemies and Weaker Enemies modifiers, Cooldown +1 is much more common than Cooldown -1 for Boss rooms.
The only modifier that you cannot seem to get in Boss rooms is the Blind modifier, as I've never encountered it in any Boss room before.
Finally, you have the Casual Effect modifier which randomly picks one of the above mentioned room modifiers except for Blind.
2. Dodge Chance: For the first turn, try to hit with low damage skills first as I've noticed the first attack is more likely to be dodged for some reason. This is my speculation only and I might just have horrible RNG.
3. Preparing for Boss Fights: Making sure your skills are ready before a boss room is vital, either drink ability potions after the last fight or refrain from killing the last enemy until your skills have recharged.
4. Skipping Rooms: Some rooms have Fast Forward doors (represented by the fast forward sign) that allow you to skip a room. The only exceptions are rooms before special events (Floor 4, 14, 24, etc.) and rooms before boss rooms (Floor 9, 19, 29, etc.).
If you are in a room two floors away from the boss room (Floor 8, 18, 28, etc.) that has one of these doors, you can use it to skip the floor before the boss. This puts you in the boss room with the Fast Forward room modifier which has no effect in combat, thus avoiding negative modifiers in Boss rooms.
5. DEF Stat: Your defense stat is incredibly important as it can reduce damage from normal boss attacks, allowing you to survive longer. As it is determined by your level, make sure you get as many experience points as you can each run by not skipping rooms frequently. EXP talismans can also help with leveling up quickly.
I hope this is helpful to anyone struggling with these bosses. If you have any additional advice or strategies feel free to comment them below.
These tips are just some things I wrote down while playing through the game and fighting the first few bosses. They won't guarantee a win but with some good RNG and a little bit of luck they can help make the fights a little easier.
Boss #1: The Skeleton General
(HP: 400 ATK: 60 DEF: 10 Shield: 50 Crit Rate: 10% Dodge Rate: 10%)
Upon reaching Floor 10 the first few times you might have some difficulty passing this boss fight with your starting set of skills. As most of them deal too little low damage and take some turns to recharge, you will most likely lose the battle of attrition.
My recommended setup for beating this boss is with a high damage skill (Nightmare), at least two heal/shield skills (Spellbinding Circle, Magic Barrier, Orb of Life) to buy some extra turns while you wait for your main damage dealer to recharge, and low CD skills (Quick Hit, Darkness Tentacles) to chip away at the initial shield and waste dodge chances (see note 2).
Quick Hit has a high enough crit rate that it can reliably damage the boss every other turn.
Darkness Tentacles deals a little more damage than a non-crit Quick Hit while having an additional stun chance (albeit incredibly low) which could help tip the scales in your favour.
Boss #2: The Corrupted Druid
(HP: 800 ATK: 140 DEF: 10 Shield: 75 Crit Rate: 20% Poison Chance: 10%)
Dealing with this boss will be much more difficult as they can poison you. Poison damage ignores both your DEF stat and shield which reduces shield skills' effectiveness in this battle.
High attack damage skills might seem like a good choice as this boss cannot dodge attacks, but their long cooldown times mean you will probably eat a lot of poison damage before you get to use them again.
Your best bet is with good healing skills, a debuff removal skill, and both burn damage and poison damage skills.
Orb of Life, Spellbinding Circle, and Vampire Fangs can offer some healing.
Hamsa is a must-have as it can remove poison and burn effects.
Venom Splash does decent poison damage over 6 turns.
Both Earthquake and Fire Wave can dish out painful fire damage over 3 turns. Earthquake does way more damage while having a low chance to trigger and a high CD (5 turns), while Fire Wave deals less damage but has a higher trigger chance and a lower CD (2 turns).
Having both poison and fire damage means that both can trigger in the same turn, dealing more damage per turn than if you stacked only poison or fire alone.
Boss #3: Elizabeth
(HP: 1400 ATK: 240 DEF: 15 Shield: 100 Crit Rate: 10% Dodge Rate: 10% Stun Chance: 20%)
For this battle the boss has a 20% stun chance, which means you can be stun-locked for a number of turns, making normal damage attacks unreliable as your skills' CD timer will not go down if you are stunned.
As with the previous boss you will need to rely on poison and fire damage skills as they can still hurt your opponent even when you are stunned.
Heart Necklace is a very good healing skill at this stage as it restores a lot of HP while also giving a decent amount of shield.
Venom Splash still is the best skill for poison.
Earthquake and Fire Wave will do the job for fire damage.
Since the boss cannot burn or poison you in this battle you should replace Hamsa with another damage or healing skill.
Additional Notes:
1. Room Modifiers: Different room modifiers can greatly influence how the battle goes.
Damage (DMG+, DMG++, DMG+++) modifiers are the worst as they greatly reduce the number of turns you have to beat the boss depending on your DEF.
Room Poison (-10 HP per turn for you and your enemy) and Darkness Essence (-20 HP for you only) modifiers are scary early on but are more manageable with good heal skills.
Health Point (HP+, HP++, HP+++) modifiers make the fight last much longer so make sure your healing and shield skills can keep up with the continuous damage.
Stronger Enemies and Weaker Enemies modifiers change both the attack and health of your opponent by +50% and -50% respectively. Although for Boss rooms the Weaker Enemies modifier is usually much rarer.
The Chained Skill modifier locks one of your skill slots at random, which can ruin your build if it locks an important skill.
The Cooldown +1 modifier makes your skills take one turn longer to recharge, while the Cooldown -1 modifier makes them recharge a turn faster (they have no effect on skills that recharge in 1 turn). Similar to the Stronger Enemies and Weaker Enemies modifiers, Cooldown +1 is much more common than Cooldown -1 for Boss rooms.
The only modifier that you cannot seem to get in Boss rooms is the Blind modifier, as I've never encountered it in any Boss room before.
Finally, you have the Casual Effect modifier which randomly picks one of the above mentioned room modifiers except for Blind.
2. Dodge Chance: For the first turn, try to hit with low damage skills first as I've noticed the first attack is more likely to be dodged for some reason. This is my speculation only and I might just have horrible RNG.
3. Preparing for Boss Fights: Making sure your skills are ready before a boss room is vital, either drink ability potions after the last fight or refrain from killing the last enemy until your skills have recharged.
4. Skipping Rooms: Some rooms have Fast Forward doors (represented by the fast forward sign) that allow you to skip a room. The only exceptions are rooms before special events (Floor 4, 14, 24, etc.) and rooms before boss rooms (Floor 9, 19, 29, etc.).
If you are in a room two floors away from the boss room (Floor 8, 18, 28, etc.) that has one of these doors, you can use it to skip the floor before the boss. This puts you in the boss room with the Fast Forward room modifier which has no effect in combat, thus avoiding negative modifiers in Boss rooms.
5. DEF Stat: Your defense stat is incredibly important as it can reduce damage from normal boss attacks, allowing you to survive longer. As it is determined by your level, make sure you get as many experience points as you can each run by not skipping rooms frequently. EXP talismans can also help with leveling up quickly.
I hope this is helpful to anyone struggling with these bosses. If you have any additional advice or strategies feel free to comment them below.