About The Deck:

I wanted something 'Grindy' since most of my decks are very aggressive. I also love commanders that add new rules to the table, and this one does both. Enter: Toxrill, The Corrosive.

A 7 converted mana cost, 7 power 7 toughness big-boi that slowly weakens everything on board until it dies.
Being Dimir gives it access to great draw-power and board manipulation, preparing for the long game.

HOW TO PLAY THE DECK

> TURNS 1 though 4

WOW That's a fast slug!
Build up your mana because Toxrill costs 7. whole. mana.
If you hit your fast mana AND something to protect Toxrill with, go ahead and go for a turn 3-4 casting of him.
He acts as a preventative measure towards your opponents casting creature spells. Then protect him for a few turns as you 3HKO someone with commander damage.

> Turns 5 through 8

Turn your 'Grind' on!
A late Toxrill is still a good Toxrill - instead of being a preventative measure it acts as a slow, inevitable boardwipe, while also turning on your 'Make it Small' cards and building up some card advantage in the form of Slug tokens.
Use cards like Gisa, Glorious Resurrector to build board advantage and beat opponents down while they have nothing to block.
Fill your board with power immediately with Clackbridge Troll or Hunted Phantasm and swing big with Slug Tokens and beaters next turn.
Speaking of Slug tokens, Sadistic Hypnotist loves them. You can keep a soft-lock on the game by simply making sure your opponents have no cards to play with.

Tips and Tricks

>When To Cast The Slug

The there are two 'best times' to cast Toxrill: Before any creatures are out, or when lots of creatures are out. So really its always a good time to cast Toxrill - WITH ONE CONDITTION:
You either have a way to recur him (Animate Dead, etc.) or protect him (Kaya's Ghostform). Otherwise you've just wasted 7 mana!
Toxrill has to stick around for the game to get grindy, so your real concern is how you can protect him while he's out.

>Making things small

You can think of Toxrill, The Corrosive as a means to a new 'economy'.
Spells that make entire boards small frogs really just read "For every creature your opponent controls, they sacrifice it and you get a slug token". Even indestructible creatures, such as Ulamog, the Ceaseless Hunger are subject to oblivion once they get Diminish'd with a slime counter on it. That being said, Toxrill won't always be out, so having access to a good amount of counter magic and removal spells is still advised.

> Multi-Purpose Cards

• Lazav, Dimir Mastermind is great value but he also makes it 'okay' if Toxrill dies; in fact, it's encouraged! Lazav will act as a second copy of Toxrill (not affected by the legendary rule), except it also has Hexproof!

• Animate Dead and Dance of the Dead can be used to steal high-value creatures from graveyards, or bring back Toxrill for a cheap 2 mana. But make sure you have a counterspell to protect it with, as this is a high-risk strategy.

• Hero's Downfall, Ravenform, Resculpt, Mercurial Transformation, and Feed the Swarm were added to get rid of pesky cards that Toxrill himself cannot touch. (Note: Murcurial Trasformation allows cards like Lazav and Gisa to copy/steal them as they die.)

• March of the Machines allows Toxrill to add Slime counters on non-creature artifacts! So now Creatures AND Artifacts are on Toxrill's kill-list. It also allows Interesting interactions with Lazav, Dimir Mastermind and Gisa, Glorious Resurrector: they die while being creatures, so you can copy or steal them!

• Sludge Monster is the 'Golden Pig' of the deck: it was made for Toxrill! Acting as a one-sided Humility that also puts all creatures on a two turn timer. Very, very strong in this deck.

> A Good Hand Looks Like...

Two to Three non-fetch lands, one or two ramp spells, a piece of filter/counter-magic, and a removal spell.
Example Hands:

A Good Hand

• Island, Swamp, Thought Vessel, Solemn Simulacrum, Ponder, Negate, Resculpt

A Great Hand

• Command Tower, Morphic Pool, Sol Ring, Mana Crypt, Mystic Remora, Swan Song, Akroan Horse

Winning with this Deck

> Death By Tiny Slug Slaps

Inkfathom Witch has some SPICY utility for them. Playing into an empty board, courtesy of Toxrill, means those slugs will slap for a healthy 4 damage. 10 slaps is a dead opponent.

> Death By Big Slug Slaps

Toxrill, The Corrosive is a 7/7. So hitting an opponent with him three times is enough for lethal commander damage.
He keeps the board clean all by himself to get through. BUT... if you want to emphasize this strategy and lean further into voltron, I would personally include Nexus of Fate and Blackblade Reforged.
The first allows you to add more Slime counters AND another attack phase. The latter makes Toxrill an easy 2HKO beater.