Took a look at the two Luther Arkwright supplements for Mythras by Design Mechanism. Few of the creatures there would suit fantasy campaigns especially Monster Island so created them in Mythras Encounter Generator.
Here are the encounters
You can find them with tags “Luther Arkwright” and “Monster Island”
Here is the introduction to Mythras Encounter Generator. It currently contains more than 3800 published encounters and more than 580 parties (groups of NPCs around a single theme). There are more than 400 feature lists (for example Curse Spirit Ability, Exotic Poison, Chaotic Feature, Medieval German Name or Appearance – Hair Style etc) that can customise an encounter. Those feature lists contain almost 60000 features in them. There are also stats for 160+ weapons.