When a Blue Bubble sees Epona, it is quite obvious from its behavior that it wants to feast on her as quickly as possible. To make matters worse, Blue Bubbles are quite threatening to Epona. Unlike most enemies, they are immune to Epona's attacks. If she rams or stomps one, it will produce a yellow flash, but the Blue Bubble will not actually take damage. In addition, Blue Bubbles attack Epona differently than Link. Against Link, they attack with an easily-blocked ramming attack. Against Epona, they are much more aggressive. Upon seeing her, a Blue Bubble quickly flies toward a thick, meaty part of her body, typically the chest, sides, or hind legs. Sometimes, it will lunge forward and take a huge bite out of Epona before quickly flying back out of reach. Other times, it will latch on like a parasite and start chowing down on horse meat before even slaying her, inflicting serious damage. These biting attacks are slash-trait attacks, and they are very effective at penetrating Epona's hide, so they drain her health quite quickly. Because Epona cannot fight back, Blue Bubbles can quickly devour her with little trouble if she gets cornered. Definitely use Link to defeat Blue Bubbles personally, rather than meaninglessly risking Epona's safety.