Heroes downfall is too expensive, it used to be playable in modern like 5 years ago but since then the format has gotten faster. You just cant afford to run a 3 mana creature/planeswalker only removal spell anymore, if your opponent plays a ragavan turn 1 its pretty much dead in hand. Even in more casual settings I'd argue its still way too clunky, especially if you only have 19 lands.

Sudden spoiling is a funny card, its good against timmy decks but its 3 mana and doesnt actually remove any creatures permanently. Maybe I am underestimating the card a bit, but 4 is definitely too much I'd play 2 at most.

Sudden Spoiling and Hero's Downfall are not playable modern cards, the removal has to be more efficient than that. Staple BR removal options would be 3-4 Lightning Bolt 2-4 Fatal Push 1-2 Molten Collapse 0-1 Angrath's Rampage. I'd also cut the Blightning.

Vampire of the Dire Moon kinda boring generic 1 drop. I assume Tinybones, the Pickpocket is way out of your budget, the cards not super great in here anyways.

Hooded Blightfang is honestly not the best card but I mean if you're playing deathtouch tribal then you should probably play it. Also interesting you chose BR because most deathtouch decks I see are BG and use Fynn, the Fangbearer. Green also gives you some better 1 drop deathtouchers like Gnarlwood Dryad and Narnam Renegade, and also a 2 drop Chevill, Bane of Monsters. Also 3 drop Glissa Sunslayer.

Zoyowa Lava-Tongue 2 drop deathtoucher. Nighthawk Scavenger 3 drop.

Elves of Deep Shadow is better than leaden myr

Unnatural Growth is super win more and a 5 drop, plus it has 4 green pips in a deck with a budget manabase of 12 forests and 8 swamps. I'd cut all 4, and if you really want 1 then at least cut 3.

Fatal Push staple removal spell that also synergizes well with all your revolt triggers. Maybe too expensive though.

Giant Growth and Might of the Masses are again win more; this isn't an infect deck. I'd replace with more enablers (i.e. creatures you can sacrifice or token generators) like Blisterpod, Tend the Pests, etc. I assume Bitterblossom is out of your budget unfortunately.

4 Ragavan is probably necessary maindeck, probably cut the street wraiths for them since wraith isnt really needed in shadow decks anymore

I don't like 4 Sheoldred, I'd run 1-2 molten collapse and 1 angraths rampage main and 1 side instead (hits one ring). They also add more sorceries for delirium.

Don't understand what Ob Nixilis is doing in the sideboard? And Nihil Spellbomb is better than Soul Guide Lantern most of the time. I also do not like shattering spree in such a black heavy deck. Also have 3 basic swamps you can just run Blood Moon over alpine moon, especially since alpine does nothing against titan. Hidetsugu Consumes All  ^Flip decent sideboard card, rhinos is not popular atm but there might be a new leyline scion rhinos deck, and of course its good against saga and affinity.

Maybe you can run Orcish Bowmasters, but the creature slots are already really cramped so I'm not sure. But its definitely better than Spyro. Maybe a single Tarfire for nethergoyf.

Fable of the Mirror-Breaker  ^Flip is pretty slow but its an enchantment for nethergoyf and basically always a 2 for 1, good in the grindy matchups.

If budget is not an issue: Slickshot Show-Off is currently the best 2-drop prowess creature in the format

Dragon's Rage Channeler + Mishra's Bauble also good in prowess decks

Birgi and Chandra are probably way too slow for a prowess deck

probe is banned lol

Paying life for growth shouldn't be an issue when playing a prowess deck since you're trying to kill your opponent as fast as possible

The most effective lifegain decks I see are ones that can gain a lot of life, but also can stack a lot of lifegain triggers with soul sisters and make big beaters like Voice of the Blessed to have a somewhat okay aggro plan, its just unfortunate that a lifegain deck can never be super competitive since it was my favorite mechanic when I started playing magic. Unless its in a more D&T shell, there are just so many decks that don't care about lifegain (pretty much any control, combo, midrange, or tempo deck).

Mutagenic Growth? Monastery Mentor may be too slow but is decent

I highly advise against running Lay Down Arms in the sb, giving your opponent life is not what you want to be doing here

This deck probably needs some sort of clock or lifegain payoff for any linear combo deck or basically anything that isn't aggro

Amulet has remained tier 0 or 1 through metas with KCI, Hogaak, Eldrazi, Oko, Mox Opal, Treasure Cruise/Dig Through Time, Faithless looting/Golgari Grave Troll Dredge, Uro, Prowess, Lurrus/Yorion decks, and to this day. The deck is always the most broken thing in modern and just avoids bans by being hard to play.

You might be interested in 30v: vintage but each deck has to be under $30