Red in Zendikar has a lot of interesting, flavorful cards. It contains one of the most aggressive creatures you've ever seen, a second printing of Chandra, and the fabled "The Land Continues To Burn" card.

Chandra Ablaze - 4rr
Planeswalker - Chandra Mythic Rare
[+1]: Discard a card. If a red card is discarded this way, Chandra Ablaze deals 4 damage to target creature or player.
[-2]: Each player discards his or her hand, then draws three cards.
[-7]: Cast any number of target red instant and/or sorcery cards from your graveyard without paying their mana costs.
{5}

Starting off with a bang, the new Chandra is one powerhouse of a Planeswalker. Her ultimate is a game-ender, her -2 ability is both an epic discard spell and a big reload for RDW, and her +1 ability is a Flame Javelin. She's already big money, so she's not a "good investment", but if RDW becomes a real deck and needs a finisher and a reload button, she could see a slight price increase. Overall she'll probably hover between 10 and 15 big ones.

Electropotence - 2r
Enchantment Rare
Whenever a creature enters the battlefield under your control, you may pay 2{R}. If you do, that creature deals damage equal to its power to target creature or player

Pandemonium was awesome because it was a free trigger. Electropotence asks a red deck to spend 3 mana and a card to do nothing, and another 3 mana to maybe squeak out a few extra damage. Great name, great flavor, terrible card. Bulk.

Elemental Appeal - rrrr
Sorcery Rare
Kicker 5 (You may pay an additional 5 as you cast this spell)
Put a 7/1 red Elemental creature token with trample and haste onto the battlefield. Exile it at the beginning of the next end step. If Elemental Appeal was kicked, that creature gets +7/+0 until end of turn.

Is Ball Lightning played right now? No. Then why would this be? Well, we have Goblin Guide, Ball Lightning, Hell's Thunder, Zektar Shrine Expedition, and this card here. We also have Bolt, Fallout, Pyroclasm, and the new Shock/Flame Javelin hybrid. It's conceivable to think that with Fae and Forgetender gone, this kind of ridiculous sligh could really take off. Run 8 fetch lands to thin the deck and trigger Zektar Shrine Expedition, and there might be a contender. Testing is needed to see if the deck is any good, and even so, Elemental Appeal has an extremely narrow use. If you like RDW and Sligh kind of decks, grab the cheap playset now in case they start being worth a couple bucks each.

Goblin Guide - r
Creature - Goblin Scout Rare
Haste
Whenever Goblin Guide attacks, defending player reveals the top card of his or her library. If it's a land card, that player puts it into his or her hand.
2/2

We discussed this earlier, but it bears repeating. This card is the stone cold NUTS. A 2/2 haste for 2 is always "good enough", and the card is designed in such a way as to ensure that the opponent is likely dead before the drawback matters. Path to Exile put the land INTO PLAY and it's good enough. This card is probably one of the best in the set, if not one of the best in the format, and it should be worth WELL over the 5 dollars for which it's pre-selling.

Hellkite Charger - 4rr
Creature - Dragon Rare
Flying, haste
Whenever Hellkite Charger attacks, you may pay 5{R}{R}. If you do, untap all creatures you control and after this phase, there is an additional combat phase.
5/5

Simply fantastic flavor, and we predict that the art is going to be mouth-wateringly awesome too. Sadly, he's the Ron to Broodmate Dragon's Fred and George Weasley, so he won't see competitive play. Feel free to Live the Dream in casual or EDH though.

Kazuul Warlord - 4r
Creature - Minotaur Warrior Ally Rare
Whenever Kazuul Warlord or another Ally enters the battlefield under your control, you may put a +1/+1 counter on each Ally creature you control.
On expeditions, minotaurs are worth their weight in gold. Fortunately for the paymasters, most minotaurs don't know how much they weigh.
3/3

A real Minotaur is worth his weight in gold. A cardboard one isn't worth the stock he's printed on. The Ally tribe just doesn't seem good, and he's no exception. Bulk.

Lavaball Trap - 6rr
Instant - Trap Rare
If an opponent had two or more lands enter the battlefield under his or her control this turn, you may pay 3{R}{R} rather than pay Lavaball Trap’s mana cost.
Destroy two target lands. Lavaball Trap deals 4 damage to each creature.

Clearly a blowout against an aggro deck using fetch lands, this card is so ridiculously cheap that it might be worth socking away a set or two just in case. The odds that it ends up being playable are low, but they are there. Sam Stoddard seems to like the card, as well as a number of other talented players. The potential is there, but it's far from a sure thing. Keep it on your radar.

Obsidian Fireheart - 1rrr
Creature - Elemental Mythic Rare
1{R}{R}: Put a blaze counter on target land without a blaze counter on it. For as long as that land has a blaze counter on it, it has "At the beginning of your upkeep, this land deals 1 damage to you." (The land continues to burn after Obsidian Fireheart has left the battlefield.)
4/4

The best flavor ever, and a serious annoyance in an EDH deck, Obsidian Fireheart is too slow for Standard. If you can get him online, the damage will quickly add up but the fact is, 3 mana is a lot for a red deck to spend without getting 3 damage up front or clearing the board. Probably going to end up a low-end Mythic that remains popular with casual players.

Pyromancer Ascension - 1r
Enchantment Rare
Whenever you cast an instant or sorcery spell that has the same name as a card in your graveyard, you may put a quest counter on Pyromancer Ascension.
Whenever you cast an instant or sorcery spell while Pyromancer Ascension has two or more quest counters on it, you may copy that spell. You may choose new targets for that copy.

That's an awful lot of work to get a few free spells. The payoff is huge, but red decks aren't known for their ability to find multiple copies of the same spell easily. The red quest that vomits out a 7/1 haste guy is better by far.

Warren Instigator - rr
Creature - Goblin Berserker Mythic Rare
Double Strike
Whenever Warren Instigator deals damage to an opponent, you may put a Goblin creature card from your hand onto the battlefield.
1/1

This poor fellow went from Zendikar's Next Top Model to Persona Non Grata in a heartbeat. He's only preselling at 10 dollars now, but it's clear that Goblin Guide is the real star of the tribe. There's just not enough tribal support to make him good, so if you can get 10-15 in trade, do so.

Winners: Goblin Guide
Sleepers: Elemental Appeal, Lavaball Trap