Your concept is inspiring me to think about a centaur tribal deck with heroic and lifegain as a theme, should be doable on the cheap and Pheres-Band Warchief is a hell of a lord. Maybe its better as pure heroic though, lifegain might be too cute...
For a budget deck, I would drop the Mutavaults, probably replace them with 2 mountains and 2 'combat tricks', like Rouse the Mob or Blinding Flare. Blinding Flare is probably more of a sideboard option but Trample can help you close out a game. Other than that, your bloodrush list looks pretty appealing to me, but I am not an expert
I'm not an expert, but I don't think the Eidolon of Countless Battles can be replaced in this deck, the synergy with Ethereal Armor and Madcap Skills is too high to ignore. Magma Jets and Lightning Strikes are not where this deck wants to go, you're not aiming for the long game, you're aiming to beat down with cheap dudes. The longer the game lasts, the bigger the chance that your opponent has some sort of boardwipe, which will screw you over.
I think a few copies of Relic of Progenitus might do you good, I'm not sure what your local meta looks like but I see a fair amount of Pyromancer's Ascension, Dredge, etc in mine. Normally I'd recommend Grafdigger's Cage instead, but since you don't want to turn off your Chandra's Phoenixes this is probably stronger. If you have a lot of burn decks in your meta, something like Witchbane Orb might be nice.
Personally I would go -1 Venser, the Sojourner for +1 Restoration angel, if your main plan is to be blinking, getting your creature back NOW seems a lot stronger than getting it back at your end-step and with 3 of him you'll still get your Venser a lot of the time. I would also stick the sweepers all into the sideboard since there are a large number of decks in Modern that don't play a lot of creatures making your sweepers into potential dead weight.
Have you considered playing some cantrips? Something like Peek for instance, or Gitaxian Probe. Peek will allow you to see what your opponent is planning and allow you to adjust your plays accordingly. If you don't mind playing it at sorcery speed, Gitaxian Probe is a strong alternative, since you can play it for 2 life if you're far enough ahead.
Personally I am playing a budget version of Delver control and the full set of cantrips (4x Gitaxian probe and 4x Serum visions) are really what makes the deck. A lot of Serum Visions' value comes from the scry to help flip delver, so I can see replacing it with an instant speed cantrip instead in your deck, but the consistency you gain from playing cantrips is fully worth the pain of cutting other cards as I see it.
I added the Grafdigger's Cages to the sideboard since I had them lying around and they seem good against a few decks, the rest is just there so I can try out different numbers of my spells in different matchups. I'll be able to replace it with a better sideboard once I get an idea of my local meta, though finding budget sideboard options may pose a challenge here and there.
Some cheap things I'm considering for the sideboard: Hibernation - I think 3cmc is a bit steep in my deck, but this may be worth it if there's a lot of green monster-y decks around Trickbind - This should help me hate out against Twin and such. Squelch - Same as trickbind, but with a cantrip stapled on instead of the split-second...not sure if that is worth it Combust - This should kill pretty much any green or blue creature out there I think? Vandalblast - To kill problematic artifacts and vs Affinity it's a great one-sided sweeper if I ever get to 5 mana. Counterflux - Against storm this pretty much reads "1UUR: Win the game" I think? I have one or two lying around. Past in Flames - I have one lying around, might give me the reach I need if a game goes long. Dismember - Not sure if I can afford the 4 life but it is premium removal Surgical Extraction - Take my opponent's win condition out completely once I've countered it. I would play at least 2 so that I can also take out their backup. Not sure if it's worth it though... Echoing Truth - Twin killer?
I intend to play the established UR Delver eventually, but since I currently do not own any Snapcaster Mages, fetch lands or Mutavaults and my budget currently doesn't have the room to acquire them, I'm putting together a cheaper version of Delver, hence the name I gave the deck.
The idea is that the 8 cantrips will somewhat make up for the fact that I'm missing the filtering of the fetches and the utility of the snapcasters.
I'm playing Grim Lavamancer to get a little of that utility back, but having multiple copies in play at the same time won't do much for me, so I'm only running 2.
I could see running 3 or 4 of Young Pyromancer instead, since multiples of him are fine, but I'm not sure what that will do to my chances of flipping Delver of Secrets, let alone what to take out for the extra copies.
The reason I made this thread is because I just can't seem to settle on the right numbers, and I keep swapping several counters back and forth. I also can't seem to settle on a sideboard.
These are the cards I am currently considering for either maindeck, sideboard or both:
Searing Blood - Probably sideboard material since not every deck will have enough targets, but when there ARE enough targets, it seems like shock and lava spike stapled together would be nice.
Dispel - One of the counterspells I'm considering. Mainly trying to decide between this and Spell Snare, they are both fairly narrow and have their uses.
Vapor Snag - If a creature passes your wall of permission, bounce it back to the owner's hand and try again. In an extreme case, it can even save one of your own creatures, although I'd say ours are pretty expendable. Maybe we want to replace it with Disperse or Cyclonic Rift, but I kinda like the fact that it's a mana cheaper.
Incinerate - I'm not sure if we need to have more burn/removal, if so this is probably the best candidate.
Nix - If I understand this card correctly, it might be a nice bit of sideboard tech to fight decks that try to cheat stuff into play. Show and Tell? Sure! I'll just counter the Emrakul you try to drop though. Have fun finding it again. Seems good if it really does work like this.
Have you considered playing some cantrips? Something like Peek for instance, or Gitaxian Probe. Peek will allow you to see what your opponent is planning and allow you to adjust your plays accordingly. If you don't mind playing it at sorcery speed, Gitaxian Probe is a strong alternative, since you can play it for 2 life if you're far enough ahead.
Personally I am playing a budget version of Delver control and the full set of cantrips (4x Gitaxian probe and 4x Serum visions) are really what makes the deck. A lot of Serum Visions' value comes from the scry to help flip delver, so I can see replacing it with an instant speed cantrip instead in your deck, but the consistency you gain from playing cantrips is fully worth the pain of cutting other cards as I see it.
4x Delver of Secrets
4x Young Pyromancer
2x Grim Lavamancer
Spells
4x Lightning Bolt
2x Izzet Charm
2x Pillar of Flame
4x Gitaxian Probe
4x Serum Visions
3x Vapor Snag
3x Spell Snare
3x Dispel
2x Remand
3x Mana Leak
6x Island
4x Mountain
2x Fairie Conclave
2x Ghitu Encampment
2x Steam Vents
4x Sulfur Falls
3x Grafdigger's Cage
2x Grim Lavamancer
2x Izzet Charm
2x Pillar of Flame
2x Remand
1x Spell Snare
1x Mana Leak
1x Vapor Snag
1x Dispel
I added the Grafdigger's Cages to the sideboard since I had them lying around and they seem good against a few decks, the rest is just there so I can try out different numbers of my spells in different matchups. I'll be able to replace it with a better sideboard once I get an idea of my local meta, though finding budget sideboard options may pose a challenge here and there.
Some cheap things I'm considering for the sideboard:
Hibernation - I think 3cmc is a bit steep in my deck, but this may be worth it if there's a lot of green monster-y decks around
Trickbind - This should help me hate out against Twin and such.
Squelch - Same as trickbind, but with a cantrip stapled on instead of the split-second...not sure if that is worth it
Combust - This should kill pretty much any green or blue creature out there I think?
Vandalblast - To kill problematic artifacts and vs Affinity it's a great one-sided sweeper if I ever get to 5 mana.
Counterflux - Against storm this pretty much reads "1UUR: Win the game" I think? I have one or two lying around.
Past in Flames - I have one lying around, might give me the reach I need if a game goes long.
Dismember - Not sure if I can afford the 4 life but it is premium removal
Surgical Extraction - Take my opponent's win condition out completely once I've countered it. I would play at least 2 so that I can also take out their backup. Not sure if it's worth it though...
Echoing Truth - Twin killer?
Here is my current list:
4x Delver of Secrets
2x Young Pyromancer
2x Grim Lavamancer
Spells
3x Izzet Charm
4x Lightning Bolt
3x Skullcrack
3x Lava Spike
4x Serum Visions
2x Spell Snare
2x Remand
3x Spell Pierce
4x Mana Leak
6x Island
4x Mountain
2x Fairie Conclave
2x Ghitu Encampment
2x Steam Vents
4x Sulfur Falls
The idea is that the 8 cantrips will somewhat make up for the fact that I'm missing the filtering of the fetches and the utility of the snapcasters.
I'm playing Grim Lavamancer to get a little of that utility back, but having multiple copies in play at the same time won't do much for me, so I'm only running 2.
I could see running 3 or 4 of Young Pyromancer instead, since multiples of him are fine, but I'm not sure what that will do to my chances of flipping Delver of Secrets, let alone what to take out for the extra copies.
The reason I made this thread is because I just can't seem to settle on the right numbers, and I keep swapping several counters back and forth. I also can't seem to settle on a sideboard.
These are the cards I am currently considering for either maindeck, sideboard or both:
Searing Blood - Probably sideboard material since not every deck will have enough targets, but when there ARE enough targets, it seems like shock and lava spike stapled together would be nice.
Dispel - One of the counterspells I'm considering. Mainly trying to decide between this and Spell Snare, they are both fairly narrow and have their uses.
Vapor Snag - If a creature passes your wall of permission, bounce it back to the owner's hand and try again. In an extreme case, it can even save one of your own creatures, although I'd say ours are pretty expendable. Maybe we want to replace it with Disperse or Cyclonic Rift, but I kinda like the fact that it's a mana cheaper.
Incinerate - I'm not sure if we need to have more burn/removal, if so this is probably the best candidate.
Nix - If I understand this card correctly, it might be a nice bit of sideboard tech to fight decks that try to cheat stuff into play. Show and Tell? Sure! I'll just counter the Emrakul you try to drop though. Have fun finding it again. Seems good if it really does work like this.