I use the Sonic Bow II on both types of that creature. Also heres a helpful suggestion when fighting the Plesiloth. The Sonic Bow is a electric based weapon great when fighting the Plesiloth but this tip will be asset as well. First before starting a quest, equip some Large barrel bomb+, large barrel bombs, and or the ingredents to make these powerful items. Next try using the Sonic bows ability to carry Paralysis coatings by epuiping the item. You see where this is going? ;) By coating your arrows with the paralysis coat, you can temporaraly immobolize the creature. Now for the conclusion, while its immobolized get in close and place as many large barrel bombs as possible around its vitals, get back, let an arrow fly into a bomb, and watch the fireworks as the Plesiloth takes a grand slam of damage! :twisted: . This is a lot of fun with friends, OH :!: by the way, if you want to capture it, its sign for capture is when its fins fold down.