Muktol

Some suggestions:
[[Ajani, Adversary of Tyrants]]
[[Ashes of the Abhorrent]]... A modern legal and faster version of [[Moonlit Wake]]. [[Proper Burial]] could also be an option as it profits from stronger creatures and lord-buffs. [[Contemplation]] could be switched against e.g. "Angel's Feather" though not an enchantment but faster and making the deck modern legal.
[[Soul Warden]]... A faster non-cat version of [[Healer of the Pride]]
[[Spare from Evil]]... A good sideboard-card, some may even play it mainboard.
[[Angelic Accord]]... Enables you to create a 4/4 Angel token at the end of your turn when you gained 4+ life this turn.

With a high number of token-producing cards I would try to raise the number of [[Intangible Virtue]] to 4 or use [[Honor of the Pure]]/ [[Spear of Heliod]] instead. Personally I wouldn't run this deck with fewer than 20 lands.

Greetings
Muktol

I know but both cost an arm and a leg when buying them. It may seem strange but I decided very early on that, while building decks on this site, I would only build such that I also would be willing to built/ buy them.

You could take a look at:
[[Hardened Scales]]...tough not really a budget-card it still worth considering.
[[Imaginary Pet]] ...has no undying but you can cast it each turn and thus push all your evolve creatures up to 4/4's. [[Greenbelt Rampager]] is a slightly different version that allows you to cast this creature twice each turn and pushing your evolve creatures.
[[Renegade Krasis]]... can multiply the number of counters in your creatures, especially when used with [[Imaginary Pet]]/ [[Greenbelt Rampager]]

Greetings
Muktol

I removed 2 [[Blossoming Defense]] to add 2 [[Vines of Vastwood]] and 4 [[Satyr Hoplite]] (I was never really happy with that card) to add 4 [[Nivmagus Elemental]]
What would you remove to add 3-4 [[Mutagenic Growth]]?

[[Chronic Flooding]] instead of [[Curse of the Bloody Tome]] maybe. Costs the same but mills 3 instead of 2.
[[Drift of Phantasms]] could also be an option to search for the maniac.
I would also include a counterspell against non-creature spells, like [[Negate]] or [[Spell Pierce]] to protect your Maniac in the last turn against removal.

[[Invigorate]] is banned in pauper:
https://magic.wizards.com/en/game-info/gameplay/formats/pauper

Both creatures only benefit from the one or two spells that you really cast (e.g. [[Maximize Altitude]] + [[Gravitic Punch]]) but not from the copies. [[Wee Dragonauts]] will still get +4/+0 if you cast those two. I think it's still a worthwhile endeavor but not as "over"powered as it first looked.
[[Opt]] as card-draw/ advantage comes to my mind to increase the chance of casting multiple spells per turn.
[[Run Amok]] could also be an option instead of [[Sure Strike]] (Trample vs. First Strike)

+1
[[Doubling Chant]] and [[Primalcrux]] come to my mind. [[Nacatl War-Pride]] could also be an option as the tokens of this creature are special and do create devotion.

[[Beamsplitter Mage]] (as single creature on the field) + [[Maximize Altitude]] + [[Gravitic Punch]] = 3 damage. With another creature on the field this becomes 6 damage, this is correct. The problem with all the other interactions, like [[Beamsplitter Mage]] + [[Smelt-Ward Minotaur]], is that you need to "cast" a spell to activate the ability. A copy of a spell is never cast but only put on the stack, so e.g. the Minotaur will only activate twice when using [[Maximize Altitude]] + [[Gravitic Punch]].

From the Comprehensive Rules:
706.10. To copy a spell, activated ability, or triggered ability means to put a copy of it onto the stack; a copy of a spell isn't cast and a copy of an activated ability isn't activated.

To link a card use two rectangular brackets before and after the cardname like [[CARDNAME]]. Cards with an apostrophe in it's name can't be displayed as links. And this also only works in the comments.

The problem with aggressive decks is that they end in topdeck-modus very fast and have to rely on what they draw. Here Viscera Seer shines as it let's you put an undesired card, e.g. a land, on the bottom of your library. I wouldn't use 4 of him in the deck but 2-3could be an option.

[[Perilous Myr]] has one big advantage over e.g. [[Tattered Mummy]], [[Ruthless Ripper]] or [[Vampire Neonate]]: It can serve as additional, most important colourless, removal. [[Undying Evil]] depends on it's usage but here this might be limited. I normally would use it to protect a precious creature from getting killed in combat or due to a removal. The problem here is that only [[Nantuko Husk]] makes sense to use it on as other important creatures will likely have a +1/+1 counter on it. Personally I would remove [[Kjeldoran Dead]] for the Angler as you can't play around the sacrifice ability. You loose a creature that let's you sacrifice something but you gain the ability to use your graveyard as resource.

For instant speed you have [[Tragic Slip]], a very potent removal even able to handle a [[Blightsteel Colossus]] (Outside pauper of course ;) ) and you should have enough sacrifice creatures to activate that morbid when you really need it. So the big question is: Do you really need the instant speed?

One thing that also came to my mind was to replace white as second colour with red to give the deck an extra speed/ sacrifice boost. Or do a second deck with Rakdos colours.

+1
[[Viscera Seer]] can provide you with a little card advantage by controlling what you draw next. [[Thraben Inspector]] is also a good card for, only drawback is that you can sacrifice him only once. [[Captain's Call]] is a little bit on the high-side with it's cc4 but it provides you with 3 tokens to be sacrificed.
Personally I would change from [[Kjeldoran Dead]] to [[Gurmag Angler]] and use [[Bone Splinters]] instead of [[Final Payment]].
If you need some life-gain consider [[Sylvok Lifestaff]], rescued me some games in my sacrifice deck.

Greetings
Muktol

If you want to stick to the theme...[[Knight of Sursi]].

A card overlooked by many Exalted decks is [[Sigil of Valor]], which is basically a cheap [[Sublime Archangel]] you have to equip to benefit from.

6yo at the computer?
I've read that it is intended as a one-drop before I postet the suggestion. The question is if the creator of the deck see's enough advantage/ potential in Edge of the Divinity to have a cc2 creature in the deck over a cc1.

What about [[Mourning Thrull]] instead of [[Vault Skirge]] and [[Edge of the Divinity]] as enchantment?

Lets say you cast a [[Lightning Bolt]] and copy it with a [[Twincast]].
Stack (Top Down): [[Twincast]] -> [[Lightning Bolt]]
Now you use [[Riku of Two Reflections]]'s ability to create a copy of [[Twincast]] and target the initial Twincast with it.
Stack: [[Twincast]] (Copy) -> [[Twincast]] (Original) -> [[Lightning Bolt]]
The copy resolves, targeting the original, creating a new copy
Stack: [[Twincast]] (Copy2) -> [[Twincast]] (Original) -> [[Lightning Bolt]]
The copy resolves again (and so on), targeting the original, creating a new copy
Stack: [[Twincast]] (Copy3) -> [[Twincast]] (Original) -> [[Lightning Bolt]]
To end this infinite loop you have to target the innitial spell, [[Lightning Bolt]] in this case, and end up with basically 3 Bolts in the end.
Stack: [[Twincast]] (CopyX targeting Bolt now) -> [[Twincast]] (Original, targeting Bolt) -> [[Lightning Bolt]]

The main problem here is: Copied spells aren't cast and thus don't count towards storm counter.
From the original rules: 706.10. To copy a spell, activated ability, or triggered ability means to put a copy of it onto the stack; a copy of a spell isn't cast and a copy of an activated ability isn't activated.

Hate to destroy the idea, but this doesn't work as intended.

Greetings
Muktol

Personally I would remove [[Sanguine Guard]] for [[Sigil of Valor]], which would also make this deck modern legal. I also would replace/ sideboard [[Highborn Ghoul]] with e.g. [[Bearer of Silence]] or [[Heir of Falkenrath]] as intimidate is a rather weak sort of evasion in my opinion.

Greetings
Muktol

2 rectangular brackets before and after the cardname: [[]]
Cardnames with an apostrophe in it ( like [[Abuna's Chant]] ) won't work properly. I also think that this only works in the comments and not in the description part.

[[Kaijin of the Vanishing Touch]] and [[Echoing Truth]] maybe?

+1

[[Boros Reckoner]] could be a modern-legal replacement for [[Mogg Maniac]] and [[Wall of Essence]] for [[Wall of Hope]].
If you're using mass-removal in combination with creatures like [[Hornet Nest]] then some haste-buffs like [[Burst of Speed]] or [[Emblem of the Warmind]] could help you to take advantage of the situation.
[[Keen Sense]] let's you draw a card whenever one of your creatures deal damage to an opponent...not combat damage but ANY damage! [[Ripjaw Raptor]] could also be an option to draw cards when your opponent attacks.

Greetings
Muktol