Devious Kelpie

{u}: Devious Kelpie becomes a copy of target creature but retains this ability.
"The largest reported Kelpie is the Loch Ness
Monster, who resides in Loch Ness, Scotland.
Its favourite form is that of a sea serpent which
leads to many Muggle sightings." - Fantastic
Beasts and Where to Find Them