Even if its more likely to be a source of bonus value or side benefit than the main defining pillar of a deck, providing another source of pressure or combat potential at such low deckbuilding cost especially one thats unpredictable to opponents makes it an excellent bonus to look for
Additional combat phases will lead to additional upkeeps , and red offers several ways to get extra combat
Zyym isnt meant for Standard, Commander, or Vintage, so theres no standard to measure it up against
Irenicus's Vile Duplication works best with decks that care about instants and sorceries and/or ones that have a commander that benefits from evasion, like Kalamax, the Stormsire
There are 17 Time Lord Doctors to choose from in many color combinations, except for black
Then you put down fetch land like Terramorphic Expanse