Muktol

What about cards like [[Cavalier of Flame]], [[Multani, Yavimaya's Avatar]], [[Ore-Scale Guardian]] or [[Terravore]] to benefit from lands in your graveyard? (aka when you can't bring them back with [[The Mending of Dominaria]])

They die to fast due to your own [[Pestilence]]. A [[Doomed Traveler]] and his token are gone after just 2 activations while [[Doomed Dissenter]] survives 3. Also you give your opponent a target for his removal, which is exactly what this built tries to evade.
There is another version of Pestilence, called Monarch Pestilence, that uses more creatures, tough mostly such ones that provide your with draw, or life, or let you return those creatures to your hand and re-use those. ([[Thraben Inspector]], [[Lone Missionary]], [[Kor Skyfisher]])

[[Nacatl War-Pride]] is a rather special creature because the tokens created are copies of it and thus have mana-costs and thus increase your deviation. If your opponent has 5 creatures on the field and you attack, your devotion is increased by 15! A [[Primalcrux]] (Which I have based my devotion deck on) thus gets +15/+15, [[Khalni Hydra]] can be played for free, [[Aspect of Hydra]] gives more power, and so on.

[[Nacatl War-Pride]], [[Primalcrux]]

"Casual" can go into a lot of directions, so some more details would be good.

In general I would strengthen the zombie-side of the deck, and add some numbers there while removing cards that don't fit to the decks theme/ strategy (Like [[Steelclad Spirit]]). From the mech-side of the deck [[Mindlink Mech]] would be interesting, when crewed by [[Bladestitched Skaab]], how effective the other two will be is hard to judge in an unfinished deck :)

Some suggestions, based on my own stompy decks:
[[Cudgel Troll]]... with enough mana it can be a real pain for your opponent to manage it. [[Trollhide]] would be [[Cudgel Troll]] in enchantment-form.
[[Snakeskin Veil]]... against control
[[Ram Through]]... I love this card. Use it with a [[Rancor]] or [[Plated Crusher]] or anything with trample, and you can remove a creature from your opponent AND deal some damage, without even having to attack.
[[Kalonian Twingrove]], [[Elephant Guide]]

Two rectangular brackets before and after the cards name: [[CARDNAME]]
Tough doesn't work then the cards name has an apostrophe in it's name and it doesn't work in the forums or when you do descriptions.

[[Think Twice]] could be replaced with [[Radical Idea]].
[[Risk Factor]], [[Sonic Assault]] or [[Geistflame Reservoir]] could also be worth a look.

What about [[Karn's Bastion]]? Proliferate artifacts, like [[Contagion Clasp]]/ [[Contagion Engine]]/ [[Sword of Truth and Justice]], could also be an idea, question is what you would remove for them.

[[Electrolyze]] could be an alternative, or maybe [[Foundry Helix]], especially if you use the tokens from the General.

Just be aware that [[Fire // Ice]] won't trigger [[General Ferrous Rokiric]]/ [[Hero of Precinct One]]

709.4b The mana cost of a split card is the combined mana costs of its two halves. A split card’s colors and mana value are determined from its combined mana cost. An effect that refers specifically to the symbols in a split card’s mana cost sees the separate symbols rather than the whole mana cost.
Example: Assault//Battery’s mana cost is {3}{R}{G}. It’s a red and green card with a mana value of 5. If you cast Assault, the resulting spell is a red spell with a mana value of 1.

301.5. Some artifacts have the subtype “Equipment.” An Equipment can be attached to a creature. It can’t legally be attached to anything that isn’t a creature.

301.5c ... An Equipment that equips an illegal or nonexistent permanent becomes unattached from that permanent but remains on the battlefield.

[[Disciple of the Vault]] is banned in pauper.

Personally I think there are some odd card-choices here. [[Keen-Eared Sentry]] to me is more of a sideboard material and why [[Steadfast Paladin]]/ [[Underdark Basilisk]]? Wouldn't some card-draw be better to increase your chance of getting the combo? [[Choose Your Weapon]] also doesn't really fir to the combo because [[Sorcerer's Wand]]/ [[Viridian Longbow]] don't care for the creatures power. [[Paladin's Shield]] could be replaced with something like [[Swiftfoot Boots]]

Some suggestions from my own goblin commander deck (Krenko tough) and a short search:
[[Anax, Hardened in the Forge]], [[Goblin Assassin]], [[Caterwauling Boggart]], ([[Goblin Chieftain]])
[[Intangible Virtue]], [[Warstorm Surge]], [[Massive Raid]], [[Quest for the Goblin Lord]], [[Call for Unity]], [[Ferocity of the Wilds]]

[[Illusionist's Bracers]], [[Magewright's Stone]], [[Thornbite Staff]]!, [[Thousand-Year Elixir]]

I was toying around with using [[Butcher Ghoul]] and [[Putrid Goblin]], the second one perhaps instead of [[Festering Mummy]]. Yes, you loose a T1 drop, but you get another creature that's simply a pain in the ass and hard to get rid of. If you bring one back with [[Ghoulcaller's Chant]] it can slow your opponents advance while serving as solid count for [[Gempalm Polluter]]/ [[Shepherd of Rot]].
Three of my testdecks could take out this decks without large efforts. Mono Black control simply has to much removal, so you will never get the numbers to effectively use you drain zombies. Mono Green stompy simply is a powerhouse that's incredible hard to stop, if you don't run a ton of removal yourself, one time I even got beaten by a [[Vault Skirge]], enchanted T2 with [[Rancor]] and followed T3 by [[Elephant Guide]]... without removal in the right moment you're helpless. Last one was Orzhov Life gain/ Drain, my personal favourite, which simply generates more life than you can drain yourself.

Thank you for the suggestions.
I didn't add [[Shambling Ghast]] because I simply overlooked it. [[Festering Mummy]] delivers a -1/-1 counter, that can weaken stronger opponents, while [[Shambling Ghast]] is more versatile and allows you to generate more mana. For the moment I added 2 [[Shambling Ghast]] and if I get the time to make some playtests, I will see which I prefer.

[[Priest of the Haunted Edge]] "only" target's creatures, so it can be a viable sideboard option, if you're up against creature heavy decks and need more removal that can be recycled with [[Ghoulcaller's Chant]]/ [[Ghoulraiser]].

I would love to hear how your deck performs, feedback, even if it#s not my own deck and myself playing, is always welcome.

[[Axebane Guardian]] would also allow the use of [[Door to Nothingness]] (or [[Helix Pinnacle]]) tough without anything to tutor it, it could be hard as 1-off to draw it.

Not even phasing would work here:
702.26d The phasing event doesn’t actually cause a permanent to change zones or control, even though it’s treated as though it’s not on the battlefield and not under its controller’s control while it’s phased out.