Winter Rose

When I think of a pony mashup I think of this one - There was an artist named Psycosis that did mashups - https://psycosis.bandcamp.com/album/psycosis-befriends-nopony also, there's another named Biff0r I recall doing vocaloid mashups back then which some I really like, like this one -

I remember traveling across some desert terrain until I came across a castle. I remember clashing sword on sword with someone. In a throne room. I think I remember Rainbow Dash dive kicking him and engaging him in battle with me. I don't remember if I defeated the adversary but suddenly an ocean came out of nowhere and devoured the desert. Now what happens next is I changed pov to Rainbow Dash. I don't remember what happened to me. The castle was being submerged and she jumps out a window as water was rushing in. I remember the other mane 6 were there for some reason and retreated down in the castle. She tried to get her wings dried off while resting on a rock and took off into the sky. I saw nothing but ocean everywhere. She landed on a cloud and stayed there for a moment. I eventually woke up after that. The next one is me in Luna's pov. She was at a beach with other ponies playing in the sand. She wanted to play with them but they were afraid of her. I remember her feeling so lonely as she stared at the others playing. She just ended up kicking a beach ball around. She then took off into the air. Another one was me traveling into another dimension with others. We eventually found a playground but I remember there was a monster there picking us off one by one. I ran away. For some odd reason I found myself back at the labs where I went into the portal to get into the dimension. The monster was chasing me there as well. And then I found myself in the dimension again. The last thing I remember was staring into Twilight's eyes as she stared into mine. When I awoke I had this feeling that she was trying to save us from something else by killing us. Strange dream. Twilight was a human fyi.

Archers of Agincourt - The Same Rainbows

My favorite would have to be Dethonator along with Archers of Agincourt, Restained Madness, Dark Symphony, Frozen Night, Kyoga, and SeriousStrings. Out of all of them it would have to be Dethonator since his music got me into the metal side of the fandom.