Being an Octopus Girl, Elly is at home with both shadow and water tiles. Her trademark skill, Electrify, relies on which tile she is in. Upon use it deals significant Electric damage to everyone within the same tile chunk as her (limited to 7 tiles of connection, however). If used in water, Electrify has the additional effect of turning a major part of affected water tiles into shadow tiles. The caveat is that Elly is not immune to this Electric damage. Her unique genetic trait, Insulated, mitigates some damage, but Electrify does such significant damage that it may become difficult to use it every fight at higher levels.
Aside Electrify, Elly's natural attack is Piercing Electric damage. Piercing is already a useful attack shape, but it being a no-cost Electric damage is a significant boon due to its massive amplification per target's defense type. Since Elly is an Octopus Girl, she's likely to engage against aquatic enemies, who take massive hits from Electric damage.