Lazav Mastermind with Gyruda Companion Casual Commander Build

This build is somewhat more restrictive because the commander has to have an even casting cost. This is not a good deck to model on MTGO because I can't tell which one of the creatures Gyruda sends to the graveyard is associated with each Lazav trigger.

As with other ETB's, you want to be able to pop it back to your hand to give it another whirl. It's otherwise a 6 CMC 6/6 critter. The ETB is what matters for this card.

Sphinx of Foresight was in my starting hand for this modeled game.

Anticipate is very useful in this deck.

Tyrant's Scorn lets me pop Gyruda for another whirl.

I can sacrifice rats from Piper of the Swarm. Here, just as an example, I sacrificed Orzhov Enforcer to draw cards off Erebos.

Lazav becoming Atemsis is good. I can tap it and draw and discard.

Bloodsoaked Altar is also really good in this. I can sacrifice/discard for a 5/5/ Demon token. 

Forever Young lets me make use of all of the other cards that land on the graveyard via Gyruda.

I can also have Spark Double become a copy of Piper of the Swarm.

Last, but not least, Unexplained Disappearance allows me to recast Gyruda.

Eutropia with Keruga Companion Casual Commander Build

The fix has been applied to MTGO for nerfing Companions. As usual, game screenshots are from solitaire games, and the card pool is Standard-only.

Minus the Enter-the-battlefield bonus, Keruga is an otherwise unremarkable 5 drop 5/4. The key to this deck is dropping Keruga when you have lots of permanents in the same turn in which you have the mana to xast those permanents AND having cards that can bounce Keruga back to your hand. The 3+ CMC limitation is not too onerous in casual Commander.

There are several cards in Standard that make this deck shine: Nadir Kraken generates tokens turn after turn to up your permanent count. You can also use the tokens as Mutate targets, but that's a secondary bonus that decreases your permanent count. Then we have two cards to bounce Keruga for additional ETB triggers: Arrester's Admonition and Rescuer Sphinx.

Europia is perfect for Kruga. With a reasonable manbase, it can be reliably cast turn 3. I would add more enchantments when expanding the card pool out of Standard.

Farfinder is a great Mutate target plus the land drop it triggers.

Keruga requires 3 extra mana. It's a late play after the nerf.

Even though I want a high permanent count for Keruga, I am also having fun testing Mutate triggers.

Eutropia gets me a counter, and so does New Horizons. Setessan Champion nets me cards.

Keruga draws a ton!! It's a lot of late game fun!

Here I am after casting post Keruga.

An early game Nadir Kraken is a beast. If not addressed, it will get your opponent a really high permanent count for Keruga.

Here I am at the turn when I put Keruga in my hand.

Proliferate.

Card draw from Keruga triggers a zillion tokens.

Atermis also triggers Nadir Kraken for tokens.

Brokkos Commander Casual Build

I worked on this deck a while back.

It's a graveyard-centric deck.

Because it is in Blue and Green, it's perfect for Proliferate. Anything with Mutate is best with tokens, and Amass is a great token strategy. As always, these are solitaire screenshots.

I also let some Devotion in as a secondary strategy, a nice-to-have.

Incubation Druid is great in this deck, and in general.

Here I tutor with Emergent Ultimatum.

And here are my selections.

There is a lot of extra card draw in this deck. I am not fully exploiting Flash here, and this is an avenue for improvement when the deck scope expands to the Modern and Legacy card pools.

Counter time!

Here is a full board of critters. I used these to test various combos. This would never happen in a real game.

Here I tutor again with Emergent Ultimatum. 

My choices. Guardian Project and Return of the Wildspeaker are awesome card-draw engines.

Early casting of Brokkos.

Brokkos equipped.