Ulamog, the monstrosity whose half-forgotten name came to be known as the merfolk sea god Ula, is emblematic of plague, the blind bonds between parasite and host, and overabundance. Ulamog is creation and destruction wrapped together in unholy harmony. Ulamog is known for his great hunger and his ability to destroy pretty much everything to satisfy its hunger.
No thought but hunger. No strategy but destruction. (Pathrazer of Ulamog)
Ulamog's tentacles, their touch like burning ice, rummaged through his soul and stung his memories one by one. (Suffer the Past)
In truth, her own faith was gone, trodden in Ulamog's wake. She pantomimed the blessing in the hope that it would inspire others to continue to struggle. (Soul's Attendant)
"Whatever the Eldrazi's purpose is, it has nothing to do with something so insignificant as us." -Nirthu, lone missionary (Ulamog's Crusher)
The last hedron slotted into place, locking Ulamog in an infinite loop of binding energy. (Aligned Hedron Network)
The lineage of Ulamog, the Infinite Gyre has its own visual hallmarks. The most notable feature is the skull-like bony plates that enshroud (or make up) the head region. The texture of bone combined with the creepy faceless implacability make the intentions of the Ulamog lineage impossible to read, and therefore make them quite frightful. It is not known what sensory organs these Eldrazi possess, or whether they have senses that defy scholars' normal understanding of perception.
The Ulamog lineage is the most limb-crazy of the three lineages. Rather than true legs, many Ulamog-lineage creatures have masses of tentacles that support torsos that themselves branch into thick arms. Their long, sinewy arms are often bifurcated at the elbow. Some Ulamog-lineage creatures lean forward, low to the ground, and drag themselves along on their arms and tentacles, letting their featureless skull-plates lead the way.
The use of otherworldly color comes up again in this lineage. Ulamog-lineage creatures mix scabby reds with luminous purples and octopoid oranges. The tentacle growths of this lineage sometimes seem to deteriorate over time, leaving a corroded or rind-like texture to their outer tissue; it is not known whether this is a natural molting process or a reaction of the Eldrazi's confinement in material existence.
Every Eldrazi in Ulamog's lineage is an extension of the titan's will. Ulamog's progeny swarm the land, draining Zendikar's mana to feed the titan's insatiable hunger. The continent of Bala Ged was ravaged by massive Eldrazi of Ulamog's lineage, its lush jungles and cascading rivers reduced to dust.