Black-red is probably the most obvious combination, with Agent of the Iron Throne, Agent of the Shadow Thieves, and Cultist of the Absolute being good background pairings for it
Beyond Zinnia, there are some impressive cards in the 99 like Jacked Rabbit and Rapid Augmenter that only further the madness that is your battlefield
What creatures to use in your decks and how
Red-Black Mordor Creature (23) Sauron, the Lidless Eye Gollum, Scheming Guide Witch-king, Bringer of Ruin The Balrog, Flame of Udun Goblin Assailant x3 Easterling Vanguard x2 Dunland Crebain x2 Mordor Trebuchet x2 Snarling Warg Gothmog, Morgul Lieutenant Voracious Fell Beast Olog-hai Crusher x2 Oliphaunt Goblin Fireleaper Grishnakh, Brash Instigator Mauhur, Uruk-hai Captain Ugluk of the White Hand Instant (2) Sorcery (6) Feed the Swarm x2 Swarming of Moria Fire of Orthanc Foray of Orcs x2 Artifact (1) Land (26) Evolving Wilds x4 Swamp x11 Mountain x11 If the green-white deck represents the forces of good, this BR deck represents Mordor and the forces of evil
