There are buffs (positive) and debuffs (negative status effects). Here is a list of the different status effects, along with detailed descriptions of their purposes. 

Green status effects cannot be removed or prevented by other effects.

Positive Status Effects (Buffs)

ATK UPIncreases Attack by 25 % 
DEF UPIncreases Defense by 45 % 
CRIT Chance UPIncreases Crit Chance by 20 % 
CRIT Damage UPIncreases Crit Damage by 50 %. 
ACC UPIncreases ACC by 30 %. 
RES UPIncreases RES by 35 %. 
AGI UPIncerases AGI by 30 %. 
CRIT ResistReduces Chance to be critically Hit by 25 %. 
InvulnerableCannot be damaged 
ImmunityCannot be Debuffed 
RecoveryRecover 15 % HP each turn 
PreservationKeeps atleast 1 HP when damaged 
ShroudedCannot be selcted as Primary Target. Will be hit by AOE. 
Guard25% of the received Damage is shared with the Caster of Guard 
ShieldReduces Damage based on Sheild Strength.

Cannot be preventend

AbsorbHeals 15 % of the Damage dealt. 
BlessedIncreases amount of recieved healing by 20 %. 

Negative Status Effects (Debuffs)

IconIdentifierEffect 
ATK DownDecreases attacks by 25%. 
DEF DownDecreases defense by 45%. 
AGI DownDecreases agility by 30%. 
CritC DownDecreases critical chance by 20%. 
ACC DownDecreases accuracy by 40%. 
Res DownDecreases resistance by 15%. 
Blind30% chance to MISS (reduced damage). 
MarkedIncreases received damage by 25%. 
SickCannot be healed. 
CursedCannot be buffed. 
StunnedCannot take action at the next turn. 
SleepAction points loads 50% slower. This results in the hero's turn coming up less often. 
FreezeCooldowns of skills are not reduced. 
PetrifiedThe next hit received is a guaranteed critical one. Effect is removed after it hit. 
BurnRecevies 3% of the targets maximum HP damage when attacked. 
PoisonReceives 10% of the targets maximum HP as damage at the start of the turn. 
BleedingReceive 10% of the caster's attack as damage at the start of turn. 
MuteCan only use the basic attack (first skill). 
BoundDeactivates passives. 
TauntCan only attack the caster with the basic attack (first skill). 
ConfusedIgnores the primary target. 
Cursed FlameReceived healing is converted to 50% damage instead. 

Special Status Effects from Heroes (Debuffs/Buffs)

IconIdentifierEffect 
HellFire

Prellbog's unique skillset. Enables Hellfire Mode for 2 turns.

Stacks

Cannot be removed

Cannot be prevented

Hellfire ModePrellbog's unique skillset and increases +20% attack and +40% agility.

Cannot be removed

Cannot be prevented

Frozen Heart

Each stack of Frozen Heart increases the Undead Dragon's HP by 15% (on top of the regular 50% max HP) when reviving. Limit: 5 stacks.

Stacks

Cannot be removed

Cannot be prevented

Heating Up

Construct's unique skillset. All enemies damage 60% ATK + 20% for each stack of Heating Up. Inflicts Burn if there are more than 3 stacks of Heating Up.

Stacks

Cannot be removed

Cannot be prevented

Mjöllnir

Thor's unique skillset. Single target damage 120% ATK. Inflicts Mjöllnir. When Thor has it’s turn again, Mjöllnir returns and inflicts 80% damage on targets with Mjöllnir.

Stacks

Cannot be removed

Cannot be prevented

Seal Anubis' Seal

Anubis' unique skillset. When an enemy with Anubis' Seal dies the entire enemy team receives 50% damage of Anubis' ATK.

Stacks

Cannot be removed

Cannot be prevented

Soulmate

Aphrodite' unique skillset. All damage Aphrodite deals heals her Soulmate by 5% of the damage dealt.

Cannot be prevented

Sphinx Curse

Used by Sphinx to mark targets for a dangerous attack. Limit: 1 stack.

Stacks

Cannot be removed

Cannot be prevented

Styx

Reduces the target's max HP by 8%. Only removed if Hades dies. Limit: 3 stacks.

Stacks

Cannot be removed

Cannot be prevented

Burrow

Increases certain skill effects of the Ice Worm. Limit: 1 stack.

Stacks

Cannot be removed

Cannot be prevented

Defense Drone

Defense Drone increase Murder Machine's defense by 3% per drone. Limit: 10 stacks.

Stacks

Cannot be removed

Cannot be prevented

 

Divine Shield

Increases damage resistance per stack.

Stacks

Cannot be removed

Cannot be prevented

Ferryman

Increases the attack power of Hades' passive secondary skill "Cerberus".

Stacks

Cannot be removed

Cannot be prevented

Feral Spirit

Increases damage and AGI for 5% per Stack. Limit: 6 stacks.

Stacks

Cannot be removed

Cannot be prevented

Wildfire

Increases damage and critical damage by 5% per stack. Limit: 20 stacks.

 

Fury

Increases Bastet's critical chance by 5 per stack (limit: 5 stacks). If Bastet has at least one stack of Fury, she counterattacks with her primary skill when suffering damage, and one stack of Fury is removed.

Stacks

Cannot be removed

Cannot be prevented

Hivemind

Increases AGI by 5 per stack. Limit: 6 stacks.

Stacks

Cannot be removed

Cannot be prevented

Hot Saw

Adds a 80% Chance to inflict Burn when attacking with the primary skill.

Cannot be prevented

Loa

Increases the RES by 10 per stack. Limit: 5 stacks.

Stacks

Cannot be removed

Cannot be prevented

The Moon

Inflicts Blind for 1 turn when attacking. Grants a Shield for 60% of its Max HP to the ally with the lowest HP.

Cannot be removed

Cannot be prevented

The Star

Inflicts Mute for 1 turn when attacking. Boosts a random ally's AP by 100% when discarded.

Cannot be removed

Cannot be prevented

The Sun

Inflicts Marked for 1 turn when attacking. Heals the weakest ally for 50% of its max HP when discarded.

Cannot be removed

Cannot be prevented

Wind Up

Increases damage by 5% and Crit Damage by 5%. Limit: 6 stacks.

Stacks

Cannot be removed

Cannot be prevented

War Forge

Increases ATK by 10% and DEF by 30%. Stacks with ATK UP and DEF UP.

Cannot be prevented

Drumbeat

A special Ability from the War Bard. Increases AGI by 4 per stacks. Limit: 4 stacks.

 

Foresight

A special Ability from Odin. Increases damage resistance by 15 per stacks. Limit: 4 stacks.

 

AP Resistance

Makes the unit fully resistant to all AP reduction.

 

Arachnid

Aids the Spider Centaur in their Abilities.

Stacks

Cannot be removed

Cannot be prevented

Bloodrage

Enhances personal Skills.

Cannot be removed

Cannot be prevented

Bunny

Increases AGI by 8%, affects skills.

 

Pain Fueled

Used to enhance own skills.

Stacks

Cannot be removed

Cannot be prevented

Blood Transfusion

Increases maximum HP by 5% per stack.

Stacks

Cannot be removed

Cannot be prevented

Soul Harvest

Increases CritC 5% per Stack and AGI by 3% per stack.

Stacks

Cannot be removed

Cannot be prevented

Buzz Meter

Increases ATK by 4% per stack (max 4).

Stacks

Cannot be removed

Cannot be prevented

Biomass

Increases own HP by 4% per stack (max 5).

Stacks

Cannot be removed

Cannot be prevented

Ignited Ego

Used to enhance own skills. Increases own HP by 25% (Cornelius Prime effect).

Cannot be removed

Cannot be prevented

Life After Death

Only has an effect when a unit dies while having this status effect. If a unit dies while having this status effect:

  • Survives, with 5% Max HP, Gains a Shield for 30% Max HP.
  • Dies when his shield value goes to 0 or after next active turn. Death cannot be prevented by any other status effects.

Cannot be removed

Cannot be prevented

SludgeIf burn is present, dispels Sludge and causes 60% ATK damage (Gnarler effect). 
DetonatorDetonates when Buster uses his Secondary skill dealing 25% true damage per stack on each enemy (max. 4 stacks per target).

Stacks

Cannot be removed

Cannot be prevented

CourageUpon killing an enemy while the Courage buff is active, the character gains 1 extra turn (Shakes effect).

Cannot be removed

Cannot be prevented

SmokeIncreases Lifesteal by 10% per stack (max 3) (Pele effect).

Stacks

Cannot be removed

Cannot be prevented

Mana ShieldHero gains 30% damage resistance (Fidget effect).

Cannot be removed

Cannot be prevented

EchoDetonates for 80% ATK once the duration runs out (Sentinel and Unique weapon: Singularity). 
Ionized

All hits are critical this turn.

 

FractureDeals extra damage during Ultimate Skill. 4% Chance per stack to hit critically. Limit: 4 Stacks. 
IrradiatedReflects 20% of damage received damage as true damage (ignores Shields). 
RiftstepIncreases Crit Chance by 20%. 
BlacklistedBlacklisted Heroes suffer from certain debuff effects if the Bonnie Bullet attacks with her Primary or Ultimate skill.

Cannot be removed

Cannot be prevented

 Rooted Cannot gain extra AP from effects and cannot gain extra turns. 
 AshIf Phoenix dies, his secondary skill deals extra damage for each stack. Limit 9 stacks.

Stacks

Cannot be removed

FeatherIncreases HP by 5% per stack (max 9)

Stacks

Cannot be removed

Cannot be prevented

LuckIncreases Crit Chance by 10% per stack (max 3)

Stacks

Cannot be removed

Cannot be prevented

Artifact CoreHero gains 50% damage resistance.

Stacks

Cannot be removed

Cannot be prevented

TemperedIncreases AoE Damage Reduction by 30%.