Unfortunately, in competitive settings we both know it's gonna be typical "lame"/boring stuff like: You splashed blue: Or you splashed white: Or, my personal favorite, if you splash green, you can have access to all my favorite removal, Graveyard staples, etc.: And I wouldn't leave feedback about "How to" without covering the obvious ones, or at least some cards that immediately cross my mind for improvements: Relentless Dead Fleshbag Marauder Surgical Extraction Feed the Swarm Dismember Necroplasm Necrogoyf Necrotic Ooze Mortivore There is a piece of my heart that wishes older Zombies had a more dangerous presence for this, like (I think) Lord of the Undead or Undead Warchief
An MP card is the most recent sale at $92, with an NM copy setting the pace at a whopping $239.99, with damaged copies dropping to much more attainable prices around $30.
Conclusion Across the board, Modern Horizons 3 has provided players with efficient, flexible, and powerful cards that do everything you want
If you want to go more of the equipment route, some great cards would be things like Stoneforge Mystic, Stonehewer Giant, and Puresteel Paladin