hydras
n. 水螅属动物；一再出现的问题；难于根绝的祸患（hydra 的复数）
例句
Let's knock down those hydras and drive them to the sea!
让我们铲除祸根，把他们赶到大海去！
So positioning Hydras to attack multiple enemies is crucial. Too good, right?
所以把海德拉放到能攻击复数敌人的位置是很重要的。
The Hydras are hard to utilise fully, but when you succeed, it is very satisfying.
海德拉很难完全发挥能力，但是一旦你成功了，就会很爽。
