On Hydra the band are more experimental, but in a good way. With guest apeparances from rapper Xzibit, Tarja Turunen of Nightwish fame, Howard Jones who used to sing in Killswitch Engage and David Pirner of Soul Asylum.
This album, like their previous other records mixes in symphonic metal with power metal and occasional gothic metal influences. Singer Shannon den Adel's voice never falters or gives in to the aggressive music.
While most of the collaborations add something to the song, some don't. "And We Run" featuring Xzibit starts out as a regular symphonic metal track before Xzibit rips it with some great rapping. "Dangerous" which is the second single off of the album features Jones is a great song and his vocals add to the song. The same is true with "Paradise (What About Us?" which is the first single and features Turunen. This is also one of album's best songs. "Whole World is Watching" features Pirner and this song could do without his vocals. It really doesn't add anything to the song.
Other highlights include "Let Us Burn" which opens the album in a catchy and aggressive way. "Edge of the World" which is a low key ballad that starts out with synths and is a great way to have fans catch their breath and relax after being assaulted by the aggressive first four songs.
The album has some guttural growls from guitarist Robert Westerholt. "Silver Moonlight" and "Tell Me Why" benefit from his growls and it gives fans of more metal sounds delight.
The album's bonus disc contains four covers and all of them are improvements on the original songs. The band's covers of "Summertime Sadness" by Lana Del Rey and "Radioactive" by Imagine Dragons are the best coves on the disc. "Dirty Dancer" by Enrique Iglesias is covered as well and they improve on it. The band also cover "Let Her Go" by Passenger.
All in all the album is an improvement on their last record. If the band keep it up the way this album is going then they'll always keep their fans. Also the band should experiment more. Metal band are not known to try new things but Within Temptation have proven that they can do that.