Zhulodok, Void Gorger · Omarthis, Ghostfire Initiate
A colorless Eldrazi ramp deck led by Zhulodok, Void Gorger, cast expensive Eldrazi spells and cascade twice, pulling two additional free spells from the deck each time.
A reprint set with four decks aimed at established archetypes: Eldrazi, enchantress, planeswalkers and Slivers.
The defending player sacrifices permanents when an annihilator creature attacks. The colorless Eldrazi deck is built to get one of these onto the battlefield ahead of schedule.
Cascade casts a cheaper spell for free off the top of your library. Zhulodok doubling cascade on expensive Eldrazi spells is the deck signature line.
Constellation triggers whenever an enchantment enters. The Abzan deck stacks nine of them, so the enchantress plan pays off more than once per card.
Changelings count as every creature type, which is how the five color Sliver deck fills gaps in the hive without losing typal payoffs.
Commander Masters is a reprint set, so the value here is the card pool rather than new mechanics. The four decks pick well established archetypes and give them a proper starting point at a higher power level than a seasonal precon.
There is no new mechanic to learn. What you get instead is density: the enchantress deck runs a real constellation count, the Eldrazi deck runs real ramp, and the Sliver deck is five colors with the mana to support it.
That density changes how the decks play out of the box. Most seasonal precons have five or six cards doing the theme and forty doing nothing in particular. These have closer to fifteen, which means the engine turns on in a normal game rather than only in the games where you draw the right two cards.
The other thing worth noting is the commander pairs. Every deck ships with two legends, and in three of the four the second one points the deck somewhere different. Omarthis wants counters on Eldrazi, Narci turns enchantments into card draw, and Rukarumel rewrites what your creature types even are.
Eldrazi Unbound is the strongest of the four and the closest to tournament ready out of the box. Sliver Swarm is the one people keep for years because every new Sliver slots straight in.
Zhulodok, Void Gorger · Omarthis, Ghostfire Initiate
A colorless Eldrazi ramp deck led by Zhulodok, Void Gorger, cast expensive Eldrazi spells and cascade twice, pulling two additional free spells from the deck each time.
Anikthea, Hand of Erebos · Narci, Fable Singer
An Abzan enchantress deck led by Anikthea, Hand of Erebos, cast enchantments to draw cards, fill the graveyard, and then reanimate them as 3/3 Zombie tokens with menace.
Commodore Guff · Leori, Sparktouched Hunter
A Jeskai planeswalker tribal deck led by Commodore Guff, deploy a squadron of planeswalkers, proliferate their loyalty counters, and win through ultimate abilities and The Chain Veil.
Sliver Gravemother · Rukarumel, Biologist
A five-color Sliver tribal deck led by Sliver Gravemother, amass an indestructible hive of shared abilities and reanimate Slivers with the Ring temptation mechanic.