So there are three main rules for this playthrough, as stated below, as well as a 4th exclusive to Pre-Hardmode.



Viral Sprout Only:
The most obvious of the three rules. I can only use the Viral Sprout as a weapon, all the way from starting the game to Draedon and Supreme Calamitas.

The Viral Sprout has alright damage, mainly since it's a Post-Plantera weapon, and it fires 3 projectiles per attack. However, its main attribute is the Sage Poison debuff; a damage over time effect that stacks in power the more Sprouts active.

The issue, however, is that the Sprouts have trouble hitting small or mobile targets since they fire gravity-affected projectiles upwards to attack, making hitting things inconsistent, and relying on a DoT debuff for bosses is unreliable.



Exterior Damage Sources:
As per usual, certain damage sources not coming from the Viral Sprout are allowed, but others aren't.

Allowed:
-Certain Accessory effects (e.g. Nebulous Core's stars, Thorns effects, Shield bashes)
-Armour set bonus minions

Banned:
-Offence-oriented mounts
-Town NPCs
-Traps (Including lava)
-Minion-summoning Accessories



Minion Slot Increases:
Since the run is based around the Sage Poison debuff, it seems only fair to allow the player to 'buff' it a little further based on progression.

I decided, based on the Sage formula, to allow +1 minion slot for every point where you would receive a Rage or Adrenaline buff in Revengeance, as well as Yharon, SCal and Draedon.

This leads to a max of +9 minion slots by the tail end of the game, but bear in mind this is a Plantera-tiered weapon with low base damage and a slow debuff against bosses with millions of health by the endgame, so even if I wanted this challenge to be easier it still wasn't free by any means



No Buff Potions: (In Pre-Hardmode)
Added so I couldn't just make Summoning Potions to offset the main weakness of the Sprouts, also because I felt I was powerful enough and couldn't justify adding more power so early-on.

This will only be the case in Pre-Hardmode, however, and will be lifted upon the Wall of Flesh's defeat




Anyways, with that aside, onto the start of the game.

Summary:
I admittedly expected that Pre-Hardmode wouldn't house much of a challenge, which was correct to a certain degree I guess. The Sprout's poison did hefty damage to bosses and could hit them easily because of their large hitboxes...

...Ironically, my issues came with the regular enemies.

Because the Sprout's attacks are unreliable, especially on their own with only 1 minion slot, even fighting Zombies and Slimes were a problem. Sure, if you hit them the debuff would likely kill them in 1 hit, but the issue was actually getting the Sprout to hit them.

So, the usual order of business happened, just slower. I got Wulfrum Armour for a 2nd minion slot... which didn't help the inaccuracy issue as much as I'd hoped, and then I went to get the Abyssal Amulet... before finding out it doesn't seem to work alongside Sage Poison.



Difficulty Increase:
★★★★
⏲ N/A



Aftermath:
-I decided to head for Scourge ASAP for Victide Armour, since its locked behind it as of the Draedon update.

Summary:
On-paper Scourge is by far the easiest boss of the entire run; a long body and fairly low health make the Sprouts reliable at hitting it, and the Sage Poison combined with their spikes should shred it, right?

Well, that's sort of correct. Yes, it did die fast, but it actually took longer than I was anticipating still considering my weapon of choice. Part of the issue came from the fact that they sometimes had trouble hitting it due to its burrowing and because they struggled to keep up with its movements.

Regardless, Scourge was a complete nonissue as to be expected.



Difficulty Increase:
★
⏲ 0:12



Aftermath:
-The player can now get Victide Armour and the Shield of the Ocean; the former for the additional bulk and Urchin minion, and the latter for the buffs granted when worn alongside Victide and for later
-You can also now get Voltaic Jelly from the Sunken Sea, granting another additional minion slot for a current total of 3

Summary:
King Slime is another boss I expected to honestly die faster since its a large, fairly slow target that can't evade the Sprouts' spikes as easily as Scourge. Once again, I was wrong.

The fight wasn't an issue, just a little slower than anticipated. Sage Poison can deal 111 damage because of my 3 minion slots, and my minions have high base damage for this point in the game, so aside from the risk of being telefragged this fight is also mostly free.



Difficulty Increase:
★
⏲ 0:33



Aftermath:
-The player can directly get the Slimy Saddle and the Slime Hook from this boss, both of which are useful
--Furthermore, the player can get Shiny Red Balloons because Calamity added a recipe for them, so you can get a Bundle of Balloons fairly easily by now

Summary:
By now I'd accepted that bosses were generally going to still take over 30 seconds to kill regardless of my minions' apparent power, so I have few notes for this fight.

I did, sadly, lose a fair bit of DPS because the Sprouts did try and target the Servants at one point... and missed a lot. Also EoC's charges could put it in the ground and thus a lot of potential damage in falling spikes could also be lost quite easily.



Difficulty Increase:
★
⏲ 0:36



Aftermath:
-The Shield of Cthulhu can now be obtained, which is the only item worth getting from this boss for this challenge

Summary:
Crabulon, for once, is actually a fairly important boss in this challenge run because of it guarding one of the additional bonus minion slots I could obtain, and hence as soon as I beat the Eye I was planning to fight it.

Crabulon actually put up quite a fight here. Despite my minions' projectile spam Crabulon did it better; with more projectiles and higher accuracy and consistency.

Fortunately, due to Sage Poison only needing the occasional spike to hit Crabulon to trigger, I still came out of this fight victorious.



Difficulty Increase:
★★
⏲ 0:56



Aftermath:
-The only thing from this boss is the additional minion slot. While the only drop I need, it is still directly useful, as it brings Sage Poison's damage up to 146 and grants a 4th minion to attack with

Summary:
The Brain of Cthulhu really does not appreciate consisting primarily of lots of small, individual hitboxes in Phase 1 as every single Creeper can be inflicted with Sage Poison individually, likely killing them rapidly, so the entirety of Phase 1 was not an issue.

Phase 2 wasn't too bad, the number of spikes kept the Brain mostly at bay and the Brain's low-ish health allowed to Sage Poison to take massive chunks of his health away consistently, making it the 2nd fastest boss of the whole run.

In fact, the biggest issue was the fact that a Perforator Cyst spawned in my arena again mid-way through the fight... and you can probably imagine that lots of projectile spam and a potent debuff made the last few moments of this fight... interesting...



Difficulty Increase:
★
⏲ 0:24



Aftermath:
-Aside from getting the Deathbringer pickaxe not much else comes of this fight

Summary:
The Perforators are probably the toughest boss yet, both because of their health and because of an annoying issue with summoner where autotarget will always try to attack the worms' tails... which doesn't help considering they're already mobile enough to burrow away from the spikes.

The Hive itself was no problem, just careful movements, but the worms were problematic for the above reasons, aside from the medium worm which really didn't appreciate getting the Brain of Cthulhu's Creeper treatment and having all its segments simultaneously dying of a very potent debuff.



Difficulty Increase:
★★
⏲ 0:57



Aftermath:
-While the player can now get Aerialite I will stick with Victide for now, primarily for the shield buffs (but also because I'm admittedly a little lazy when it comes to crafting Aerialite)

Summary:
So, my biggest problem with this fight wasn't the boss, nor its minions, nor even the jungle spawns, nor even my Terraria, but in fact my actual hardware.

My keyboard actually gave out part-way through attempt 1, no longer letting me press A or S, so I had to lose the first attempt because my arena wasn't the most grapple-friendly.

After that, though, I had my revenge as the Viral Sprout is basically a hard-counter to this boss; Sage Poison bypasses Queen Bee's ever-stacking defence and Queen Bee's particular positioning allows me to manipulate her to move directly into the falling spikes' paths.

I was even able, on my 1st non-keyboard-death attempt, to actually no-hit it which was cool.



Difficulty Increase:
★
⏲ 0:52



Aftermath:
-Bee Armour is actually surprisingly useful here, since it grants 1 more minion slot my other armours didn't, bringing me up to 5 minions and a cap of 182 Sage Poison damage

Summary:
Skeletron proved to be a bigger issue than I was anticipating, almost exclusively because of his skull. The hands were no issue at all, taking only 15 seconds before the projectile spam and Sage Poison proved too much for them, however the same could not be said for the skull.

Skeletron's skull is actually immune to Sage Poison, and thus I was forced to solely rely upon the raw damage of my minions which, while a little above average in terms of damage, was unreliable due purely to how they attacked.

My main method of dealing with the skull was circling it to maximise the amount of spikes that hit it. Fortunately, this worked, and the fight wasn't too big of a hassle in the end.



Difficulty Increase:
★★
⏲ 1:01



Aftermath:
-In the Dungeon I can get the Cobalt Shield to upgrade into the Obsidian Shield, granting knockback immunity.
-Additionally, the Dungeon grants me access to Bewitching Tables. While this is a buff akin to a potion, it isn't a potion and thus wasn't actually banned by my initial set of rules
--With this potentially shady rule dodge, I now have access to 6 minions and thus a cap of 217 Sage Poison damage

Summary:
Both of Slime God's main phases have both their own sets of strengths and weaknesses against my Sprouts, so I'll address them individually.

The large slimes were a problem because, as with Skeletron's skull, they were actually immune to Sage Poison. Not sure why these were specifically given immunity considering you would never normally ever use this weapon against them, but regardless. Fortunately, spike spam prevailed and I could still deal decent damage just from sheer projectile quantity.

The core, on the other hand, was harder to hit but actually vulnerable to Sage Poison. Not sure why the lower-health member was the one without the immunity to the high-damage debuff, but I'm not going to complain. Generally fighting the core wasn't an issue since I could lead it through a cloud of falling spikes and let Sage Poison do the rest.



Difficulty Increase:
★★
⏲ 1:31



Aftermath:
-The main thing of note is the addition of another minion slot due to Slime God being the other Pre-Hardmode boss to grant a Revengeance buff. This brings me to 7 total minion slots, or 252 Sage Poison damage
-The Jelly-Charged Battery was also useful here, granting additional buffs to help the minions' raw damage
-I decided not to opt for Statigel Armour, since I'd have to lose a minion slot if I did so and thus lose both a Viral Sprout and roughly 35 Sage Poison damage

Summary:
Wall of Flesh was another Crabulon situation, where the main boss wasn't as much of an issue as its frequent use of minions. The Hungries meant I couldn't consistent hit the Wall with autotarget, but manual target meant I'd have to keep pulling them away from the wall to deal with Hungries.

Eventually, after travelling about 500 blocks across my bridge, I did defeat the Wall, but I wasn't in good shape afterwards and was at only around 100 health.



Difficulty Increase:
★★
⏲ 0:50



Aftermath:
-The player can gain +1 Accessory Slot from the Heart
-The Summoner Emblem is recommended for later
-The world will now be in Hardmode, allowing the player to progress further in their challenge...

So that was the first of three parts of the Viral Sprout only challenge.

I will try to get the other two done soon, since in the time I've been procrastinating working hard on this I've actually completed a whole new run which almost got this page cancelled, however I decided that since I'd completed it, I should at least share my findings.


Anyways, with that, I hope you enjoyed and I hope to see you in the next part when it's out

See you then :)