Risen Reef is much too good.

With this deck I'm trying to maximize reef activations with Quasiduplicate and Thunderkin Awakener. I'm not playing some of the individually strong cards like Nissa, Hydroid Krasis, or Cavalier of Thorns that usually show up in Elementals. Instead, this deck goes for a more linear and combo-deck-like game.

The usual win condition is some combination of a wide attack, Omnath to the face and a Quasiduplicate or two on Omnath (again to the face.) Jace is present as an alternate win condition because this deck mills itself out when it goes off, but I'm finding that I use him less often now in favor of the Omnath kill. If I cut Jace, I'll probably replace him with Hydroid Krasis or a couple of lands (I'm leaning toward the lands. 28 lands and 8 mana dorks seems pretty nuts, but hitting lands with Reef is the best.)

Tips:

• Mulligan pretty hard for Risen Reef. Acceptable reef-less hands are those with acceleration+Omnath+elementals (win through tempo/value), or acceleration+multiple red hasty elementals (win by dumb 1 attack beatdown.)
• You can play/copy multiple Omnaths just for his ETB damage. Unless you're against bounce, sacrifice the non-token Omnath for potential ressurection by a buffed Thunderkin Awakener.
• You generally want Scampering Scorcher in your graveyard as it's a great target for Thunderkin Awakener. Block, attack and discard to Quasiduplicate accordingly.
• A very common line is to have your first Reef killed then Thunderkin it back into play next turn. From there you can Quasiduplicate the resurrected Reef, and it will stay around after the resurrected one is sacrificed. Alternatively, you just play more elementals before EOT for the reef triggers.
• Quasiduplicating Healer of the Glade multiple times is often a winning line versus RDW. This plus it being the best 1 mana way of triggering reef have led me to keep it in the deck even though it's a "bad" card in a vacuum.
• Scampering Scorcher giving all of your elementals haste can let you use your newly played Leafkin Druids for a bigger turn.
• You'll frequently need to choose whether to play/copy a  second reef or a scampering scorcher. A second Reef gives better long-term prospects (next two turns, especially versus heavy spot removal) while the scorcher will give better immediate results (next turn.) Figure out how much time you have and play accordingly.
• Don't forget that you can choose to draw a land with Risen Reef instead of putting it into play tapped. This can give you an extra mana if you haven't dropped a land yet.