Agent51

Its going to be hard to get 5 mana on the board with 19 land you will end wit mulling a lot of times to get 2 , 3 land in your start hand.
Looking at your mana curve it the deck could use 22 lands maybe 2 Nykthos, Shrine to Nyx.
Could be a idea to take down your 3 and 5 cost to get some more 1 and 2 cost for the early game protection.

perhaps a Command Tower land if its not going to make it over budget. Need to compliment you on your budget series of decks love the flavor of them

Something like Amoeboid Changeling could be fun with the commander you are running to steal creatures

He is nice to get the big beaters and keeping them until the point you want to sacrifice them.

Swap mana leak for counterspell? like the theme

Hmm Bazaar Trader. Now i own your creature

Well since its a all land deck how about Kessig Wolf Run

may i sugest terminate over murder

Aaah sorry didnt notice it was modern

Love the idea of the no land deck been tempted to make a deck with no lands, have a copple of cards i can recomend for mana.
Elvish Spirit Guide , Simian Spirit Guide , Chrome mox.
Perhaps thoughtcast to draw a bit more

Reforge the soul would be nice in here a lot of draw and discard

you should add Favorable Winds and Fog Bank. and some more mana leak

anything to tap stuff would be useful like blinding mage , master decoy , Gideon's Lawkeeper

found something that may also be fun Soul Foundry may still mock up your mana.

Something in the line of Followed Footsteps could work nicely here my only concern is that it is a 5 cost and a bit slow but great deck

Sleeper agent could be fun with Pillory of the Sleepless but not sure what to swap for it cool deck

goblin war strike may be a good card in this deck.

This would be fun with a fling in there since you got the fire cat and ball lightning but cant think of anything to take out

its lands that generate either red or white mana in this decks case like Sacred Foundry , Clifftop Retreat.
so example
4 x evolving vilds , 7 mountain , 7 plains , 4 clifftop retreat and you got 22 lands

looks like you could drop 3 lands keep the wilds perhaps get some dubble lands.
Would recomend dropping some of the single cards.
I am no huge fan of Canyon Minotaur , Bladetusk Boar for example.