NeverDying BG (In-Depth) (Modern)

An alternate version of my deck " Undying --> Remove counters --> NeverDying ", no red anymore for an easier manabase, the core concept works well in BG.

The core idea :
-> Play creatures with Undying (Young Wolf, Strangleroot Geist, Butcher Ghoul)
-> Sac them for value (Viscera Seer, Evolutionary Leap)
-> Remove the +1/+1 counter on them gained with Undying using Retribution of the Ancients to repeat the loop.
---> Overwhelm the enemy with value or creatures he can't kill, or just abuse saccing with Blood Artist

Undying Creatures :

• Young Wolf, simple staple.
• Strangleroot Heist, strong and aggressive !
• Butcher Ghoul, worse wolf, but fill the gap.
• Demonlord of Ashmouth, flying finisher ?

Sac outlet :

• Evolutionary Leap, just get more and more creatures.
• Viscera Seer, free instant sac outlet that filter your draws !

Pay-offs :

• Retribution of the Ancients, it's just amazing. On top of being the perfect piece of the synergy : ONE black mana to remove at INSTANT speed ANY NUMBER of counters FROM ANY NUMBER of creatures, it's also act as a removal !
• Grim Haruspex, more cards. It's still shaky, I'm hardly able to really make use of it. Might cut.
• Desecrated Tomb, an army of Bat tokens !
• Yahenni, very hard to remove, can grow to become an important threat.

Wincons :

• Blood Artist, succ their life to death with self-sacrificing !
• Westvale Abbey, sac those piled up creatures for an aggressive finisher.
• Overwhelm the opponent with Undying creatures, or Bat tokens

Tools :

• Duress, gotta discard those noncreature threats !
• Tragic Slip, -13/-13 for B for creatures too big for Retribution of the Ancients.

About the mana base :
I haven't finished building it myself, I admit, but it's very important, you really need dual land early. So you can make play like
" T1 Retribution of the Ancients --> T2 Strangleroot Geist ".
You also want to have both green and black mana available to use Retribution of the Ancients and Evolutionary Leap !
Early game can really be clunky with just regular lands, waiting for a 2nd swamp to drop so you can let go the black mana reserved to use retribution and finally cast another black card.

Tricks :

• Sac your creature in answer to removal to make the spell fizzle. Doesn't work on wipes.
• Sac your tapped creature to return it untapped if it has no counter, surprise blocker !
• Retribution, Evolutionary Leaps, Viscera Seer all works at instant speed, make use of it.

Weaknesses :

• Cards that exile creature, like Magma Spray. You can dodge it by saccing to fizzle if the option is available. Sadly, Anger of the Gods is your worst enemy, your nemesis.
• Cards that exile creatures entering the graveyard, like Leyline of the Void. It totally kills the combo.

Sideboard :
Theorical, I haven't played it.

• Hardened Scales, make your creature bigger threat and more resilient to cards like Anger of the Gods.
• Heroic Intervention, need some protection from those exile wipes.
• Languish, a regular wipe. Our creatures dodge it if they don't have counters ! Use Damnation if you have the budget.
• Lost Legacy, get rid of that toxic counter card from the opponent's deck.
• Naturalize, get rid of artifact/enchantment that mess with use combo, like Leyline of the Void and Rest in Peace.
• Nihil Spellbomb, an answer to graveyard based deck. We doesn't care if our get exiled as our creature don't stay in it.

Maybeboard :
Interesting cards, to try.

• Abrupt Decay, removal for people with mOnEy.
• Blasting Station, repeatable ping ! The drawback is that it untap on ETB, and not death, it's less practical.
• Lightning Coils, really great finisher, you can stack it to create more than five elementals, then sac them for value at end of turn ! It's great, but I moved it to Maybeboard because it doesn't synergise very well with creature tokens.
• Mind Slash, we go control now. Never tried, but might wield interesting result, note that it can make the opponent discard ANY card.
• Vorapede, potential big finisher with Undying.
• Ooze Flux. Offer the same smooth counter removal than Retribution, but way more expensive. I think it's not worth it.
• Spawning Pit, instant free sac outlet. You can easily stack counters to make more tokens. Drawback is that it's not a trigger, and you need to sacrifice the creature with it (So no viscera seer or evolutionary leap). Allow you to survive hardwipe like Anger of the Gods by saccing everything to it and make a new board out of it next turn.
• Golgari Germination, Decrepated by Desecrated Tomb in this deck, still worth the mention.

Also, this is a janky deck from my own brew. I barely play any Modern. I don't know if this deck can perform well outside of kitchen table. It's also budget, as I am a cheap stake (Except for a part of the manabase sadly).