The Giga Mermaid is the second boss that appears in Half Genie Hero. She is the Queen of the Mermaids.
Pirate Queen's Quest
She manages to get recaptured by the Techno Baron and put under mind control.
Boss Fight & Strategy
Initially, the Giga Mermaid is chained to a pair of massive pillars, struggling in vain to free herself. Using the platforms and chains around the pillars, Shantae must destroy the six locks connected to the chains holding the Giga Mermaid.
To complicate matters, the Giga Mermaid periodically releases electricity-based attacks from the gem on her forehead. Initially, she fires a massive orb that slowly moves towards Shantae; the half-genie heroine will usually have to abandon her attack on the locks to avoid being hit. As the battle drags on, the giant mermaid may fire several smaller orbs that move towards Shantae in short bursts; once again, she should abandon her attack on the locks in favor of leading the projectiles around the arena until they vanish. She can also summon lightning bolts that travel around the arena; Shantae can use the platforms to keep ahead of them.
When the last lock is destroyed, the Giga Mermaid will break free of her chains, destroying the pillars in the process. After a short lull, the second phase of the battle begins.
Enraged by her captivity, the Giga Mermaid continues to attack Shantae despite being freed. She mainly attacks by appearing on either end of the dock and summoning lightning; either a single bolt from her gem or a barrage of bolts that strike the ground. The former is telegraphed by a glow in her gem, while the latter is signaled by markings appearing on the ground; either way, Shantae should make sure she's out of the line of fire. She can also dive underwater and attempt to slam her tail on Shantae; she'll pause just before striking, so use that time to get clear.
In between dodging attacks, Shantae must attack the Giga Mermaid's gem to deplete her health. This is primarily accomplished by using the structures that briefly emerge from the water when the Giga Mermaid appears on the dock; Shantae can climb up the structures and jump at the boss to attack her gem. Spitfire is an effective alternative for dealing more damage in a shorter amount of time, but magic limits could make it difficult to finish the Giga Mermaid in this way.
Giga Mermaid's attacks have been modified to increase the difficulty. In her first phase, she attacks more frequently, and her projectiles move faster. Her lightning attack will now instead strike the top-left / top-right of the stage and will travel in the opposite direction around the stage (counter-clockwise if top-left, clockwise if top-right).
In her second phase her lightning strikes will attack more quickly and the hook/platform stage will be risen from the ground for a shorter amount of time.
Giga Mermaid is initially hostile, due to a combination of mind control and being restrained against her will by the Techno Baron. This rage persists even after she's freed from her chains, causing her to attack Shantae with relentless tail slaps and lightning magic. Once calmed down, however, she appears to be rather friendly and generous, even offering Risky Boots a reward once the Queen of the Seven Seas saves her from reimprisonment at Techno Baron's hands.
The Giga Mermaid's eyes and forehead gem appear to change color with her mood - blue when calm, red when enraged.