For non-whale anons struggling with Heroic Mode, here is what you need to know. The mode puts 2 relevant debuffs on your dolls:
Data Erosion
>Your dolls takes 15% of their max HP as damage at the end of their turn.
>If they end their turn without being within 2 tiles of an ally they take another 20% max HP damage on top of that.
>The damage cannot be mitigated.
You play around this by just ending your doll's turn within 2 tiles of an ally and by bringing a healer. It's that simple.
>Disconnection
>Your dolls get this debuff at the start of every turn.
>It reduces their attack by 80% until they perform a single target damage active attack.
>i.e. their skill 0 basic attack, or any single target attack.
Disconnection is the big one you need to pay attention to. To play around this, you need dolls that have the following:
>Support Attacks
>Counter Attacks
>Interception
>Extra Action that can follow up on a single target initial attack
The goal is to do a single target attack as your doll's first action every turn and then follow up with whatever they can do as an extra action or out of turn attack afterwards. Here are some Dolls you can use and how to use them in this mode. Not an exhaustive list, just what I have off the top of my head. As long as the doll has anything I mentioned in the greentext above she can be used.
Makiatto
>One of the best dolls in this mode
>At V1 her S1 attacks twice. The first attack cleanses the ATK debuff and the second attack does full damage, usually killing the target.
>She then follows up with two interceptions out of turn which will deal full damage.
>A well raised V1 Makiatto will kill 3 enemies per turn on most stages
>At V0 she is still useful for her interceptions, so don't count her out.
QJ
>Use her S1 as it's her only single target ability. It will deal no damage but her out of turn support attacks will then deal full damage and be buffed from her S1
>If S1 is on cooldown, then use her basic attack. Do NOT use S3 or her ULT as they will not cleanse the debuff and she will end up doing no damage with her support attacks
Sharkry
>Can work with other burn allies since she has support attacks
>Her S1 overburns and procs her own support attack so she can deal damage on her turn and out of turn with her additional support attacks.
Vector
>Use any of her abilities on her turn and position her to do support attacks after
>You need allied burn dolls to proc overburn for her support attacks, but she will do very well in this mode
>Her S1 does fixed damage if you meet the conditions for it and will chunk enemies pretty hard
>Pairs well with V3 QJ for overburn procs
Centaureissi
>Support attacks
>Makes entire team invulnerable for one attack
>Global heal for the Disconnection debuff
[Expand Post] Tororo
>Her first attack will be debuffed but her two follow up attacks will do full damage
>Despite the debuff her first attack will still hit pretty hard with Springfield buffing her
>Careful not to end her extra actions more than 2 tiles from an ally or she will end up dying from the Data Erosion debuff
>MUST bring Springfield for her to work
Springfield
>Use her as normal, her bird deals counter attack damage based off of Springfield HP so it is not affected by the Disconnection ATK down debuff!!
Cheeta
>Ult to buff your allies then follow up with S1 to cleanse the ATK debuff so she can deal full support attack damage out of turn
Sabrina
>only worth bringing at V5 really
>can tank, can counter attack
>you should ult and then basic attack to cleanse the debuff and she'll deal full damage with counters
Nagant
>With her expansion key she isn't bad actually
>Her skills are all single target and will stun the enemy and cleanse the ATK debuff
>She'll then attack out of turn on enemies who move within her range and it will deal full damage
Mosin Nagant
>she support attacks so she works
>use any attack in her kit on her turn and then her support attacks will do full damage
>her paralyze is useful too