Lords of Tarkir: Faction Mechanics
WB Dromoka - Defer: Creature with Defer taps and gives itself -X/-X in order to give target creature +X/+X till end of turn. Uncommons & rares: additional bonuses. Flavor of a large, hierarchical empire where an elite draws on the resources of the lower classes.
UR Ojutai - Deceive: If you cast an instant or sorcery spell this turn, you may cast this creature for its Deceive cost as if it had flash. It gains haste. Return it to your hand at end of turn. Uncommons & rares: ETB effects. Flavor of a trickster, decoying and deceiving, darting in to steal something and fleeing before they can be caught.
BG Silumgar - Possess: Pay M, Sacrifice this creature: Manifest a card from a graveyard under your control. Uncommons & rares: bonus for sacrificing creatures you control but don't own. Flavor of a creepy expanding hivemind that doesn't care whether something is alive or dead as long as it can be put to use. Bonuses for sacrficing creatures you take control of (can manifest from opponent's graveyard w/Possess, don't need to seize an opponent's creature on board).
UG Atarka- Soulwalk: Pay M: Exile this creature. Create an X/X token (optional special abilities). When that token dies, return this creature to the battlefield." Uncommons & rares: nicer tokens, cheaper costs. Flavor of a dream-quest, astral projection. Requires you to find your own sac outlets to get back the original if you want it. Exiling the token will exile the original (kill the dreamer). Temur shamans often use ice and rock avatars for this purpose.
WR Kolaghan (work in progress) - Enlist: Creatures get bonuses for other enlist creatures and Chosen creatures under your control. Chosen creatures only get bonuses from Dragons. Uncommons & rares: chosen, dragon, maybe bonuses based on number of creatures with Enlist. Flavor of an army working together with a strict ranking.