When people think of the Onslaught Block, the cycle of fetchlands come to mind. But, those aren't the only things to return to Khans of Tarkir from that block. It was also the debut of Morph and has since been revisited in Time Spiral Block.
Perhaps the most significant change in Khans of Tarkir is the revision that creatures with Morph costs of 4 or less now no longer trump each other. If you haven't read Marshall Sutcliffe's article, it might be a good time to check it out here. If you're too lazy to check that out, here's a screenshot of the article.
What this really means is that there is a new threshold being set. Five is now the new three. Your morphs are safe against each other before five mana, either trading or bouncing off each other with no harm. However, at five mana, anything could happen and you're no longer covered by the insurance policy. Dang...
Perhaps the most interesting twist on the decade old mechanic is the cycle of five creatures that you can flip over by simply revealing a card of the appropriate color. At the price of giving away information, players get to turn up these five dudes without any mana requirements.
Snapcaster Mage Tiago Chan, as well as Grand Prix Kuala Lumpur finalist Ryan Young shared with me that they especially love Ruthless Ripper. It's essentially an upgrade to Typhoid Rats. It's a morph that you can comfortably attack with and it trades with everything your opponents put in the way. On defense, it trades with everyone too. The "lose 2 life" trigger is an awesome bonus as well.
For the very first time in Magic history, Khans of Tarkir features three-colored morphs, and in the wedge color combinations no less. While not particularly exciting in Constructed, they are high in impact in Limited. Due to their demanding mana costs, they had better be worth every penny.
In particular, Gold Level Pro Ken Yukuhiro singled out Abomination of Gudul as his favorite. "I like to draw cards," was the response. Pure and Simple. At three power, it conveniently dodges Smite the Monstrous and with four power, it withstands Bring Low, two of the most common removal cards in the format. The added bonus of fueling delve is another of the reasons to love the card. Even if you stick Debilitating Injury on it, it becomes a pseudo Jeskai Elder with flying, which isn't half bad at all.
Some of the most terrifying Morphs in the format are in the rare and mythic rare spot though, so be glad you won't be encountering them as often. My personal favorite, as well as Tomoharu Saito's, is Ashcloud Phoenix. It's great on offense and defense, and serves as a stalemate-breaker. "I don't think it qualifies as a Morph because I would never cast it face down," Saito said. "Usually I cast it on Turn 4 and the game is over so quickly."
Quirky Kuo Tzu Ching says that his favorite Morph is Kheru Spellsnatcher, quickly resulting in a derisive and condescending snort from a nearby Lee Shi Tian. "You might be dead before you get to counter anything. I prefer Wooly Loxodon any time." I had to stay on the fence because I have no clue who is right and who is wrong. But for sure, I think Malaysian National Champ Raymond Tan is right about Sagu Mauler. That card is the nuts!
Lastly, there is one Morph that is good enough to play in just about any deck regardless of its color combination. I think Witness of the Ages deserves an honorable mention!