Here's a short video showing you exactly how to easily get 10 Hive Major/Ultra kills with a Wormsinger Rune towards Eris' bounty. You can obtain a Womrsinger Rune by killing enemies on the Dreadnaught, if you haven't got one on hand, ask a friend. Usually there is always one in someone's inventory. By then activating the Wormsinger Rune on the Dreadnaught, the event will spawn plenty of Hive Majors and Ultras. Be careful not to die or kill the Champion before you have killed at least ten Hive. Hope this helped!