I'd guess your finding the deck slow, and not having enough lands to cast a lot of your creatures.
You have a lot of 5+ casting cost creatures. Sure you have
Quicksilver Amulet
to cheat them in, but it doesn't help until you draw it.
The deck feels really scattered.
Hellrider
really likes a lot of small guys to capital ize on his ability, but you don't have many. You have 3
Vexing Devil
which realy game is probably rarely a creature, and 4 other rather boring 1/1s.
Dynacharge
also like a lot of little things.
Ranger of Eos
also loves 1 casting cost creatures.
On the flip side you have
Day of Judgment
and
Terminus
. These want you to be playing few creatures, and are only used when your opponent has too many out.
You need to step back and ask yourself a few questions.
1) How do I want to win?
2) How fast do I want to win?
3) How will I make sure the other deck doesn't win?
I'd guess your finding the deck slow, and not having enough lands to cast a lot of your creatures.You have a lot of 5+ casting cost creatures. Sure you have Quicksilver Amulet to cheat them in, but it doesn't help