If you don’t know who she is, I suggest watching these videos that showcase her in game.
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Dr Coyle
“I’m unstoppable!”
The Rad Scientist Dr Coyle uses her mastermind techniques to obliterate her enemies. She won’t stop until she reaches the top!
Stars: 
Role: Damage
Position: Front
Trial Team: Yellow
Entrance: Teleports into her position
Victory: Maniacally laughs
Defeat: Crosser her arms angrily and teleports away
Attack: Extends her arms to her target, dealing damage
White Skill: Hedlok Scramble (Fantastic Damage)
Passive: At the start of each wave, the player chooses which ARMS Dr Coyle uses on each arm. She unlocks the LokJaw at this rank. Every 3 basic attacks, Dr Coyle blinds the enemy damaged for 5 seconds with this ARM. While on auto, the ARMS set are randomized. Dr Coyle also targets 2 enemies, if possible, with her basic attack.
Active: Dr Coyle summons her masterpiece, Hedlok, to clamp onto her head and use for battle. While she has Hedlok, she heals X HP, her armor is increased by 400%, she targets all enemies with her basic attack, and deals X additional fantastic damage with her basic attack.
Green Skill: ARMS Rush
Passive: Dr Coyle unlocks Parbola at this rank. Every 3 basic attacks, Dr Coyle stuns the enemy for 5 seconds with this ARM.
Active: Once Dr Coyle falls below 40% of her Max HP, she gains X basic damage and 300% attack speed for 15 seconds.
Blue Skill: Advanced ARMS Technology (Fantastic Damage)
Passive: Dr Coyle unlocks BrrChuks at this rank. Every 3 basic attacks, Dr Coyle freezes the enemy for 5 seconds with this ARM.
Active: Every 6 basic attacks, Dr Coyle gains another ARM on either side of shoulders, and can will target a 3rd enemy. This deals X additional damage and disables the enemy depending on what ARM is selected.
Purple Skill: Rad Scientist
If Dr Coyle were to take 30% of her Max HP in a single hit or is shielded, she becomes invisible for 6 seconds. If she activates this skill while shielded, she increases the shields HP and duration by 100%.
This has a chance to fail when damaged by enemies or if the shield came from allies above level X.
Red Skill: [NAME REDACTED]
Each time an enemy is debuffed, Dr Coyle gains 120 energy.
Dr Coyle will prefer to target non-debuffed enemies with her basic attacks. The first time an enemy is debuffed by her, the duration is extended by 5 seconds and the enemy is dealt X additional damage. If all enemies are debuffed, she will target the enemy with the least amount of debuffs.
Additional Stat Boosts:
+X Max HP
+X Skill Power
+X Reality
Friendship Disks:
Dr Coyle-Syndrome
Mastermind Plans
Debuffing Twice Deals Big Damage
+X Max HP
• When an enemy is debuffed by the same debuff while already debuffed, they take 5% (+5% per star level) of their Max HP as Fantastic Damage.
• Dr Coyle can deal up to X damage with this disk.
Dr Coyle-Megavolt
Electronic Flow
Longer Hedlok
+X Armor
+X Basic Damage
• If Dr Coyle KO’s an enemy while she has Hedlok, them Hedlok will stay on Dr Coyle for 1.5 (+1.5 per star level) seconds longer.
• Hedlok also increases her reality by 40% (+40% per star Level)