The key to Doomsday, in my opinion, is the same as it's always been: Kill your opponent the turn you cast Doomsday.
Unfortunately, an On-Board Ravager+Ballista makes that impossible. Also, I don't believe Doomsday is a Dark Ritual deck. If anything.
It's no secret that I love me some Doomsday, so I will share some tips with you; shout out goes to David Szatkowski, who I played at Eternal Weekend at 4-1, so at the time he was doing well and made me realize I really wanted to play the card again.
How do you replace 3 Gitaxian Probe and 3 Gush?
The key here is to play at least 2, and maybe 3 Sensei's Top. The card replaces the top card of your Library, so it can act as a Gush essentially, in that you stack your deck with the standard Gush kill with Gush as the top card, and it allows you to win easily. Sometimes setting up Preordain/Ponder/Brainstorm stacks are tough, so this is a big deal.
Draw Gush. Stack is now
Sensei's Divining Top
You Gush, then Ancestral, Etc.
Removing 6 cards from our deck via Restrictions, while the format is also changing from having a Prison Deck to having a hyper-fast Affinity deck does more than just make us say 'What 6 cards can I play in place of these cards?". We have to entirely redefine the path our deck is designed to take until it's critical turn, how our deck interacts with the current metagame, and we have to determine exactly what cards assist us in taking that path.
This card is giving me headaches trying to figure out exactly what doomsday piles you can play with this card in play, because there is a vast difference in when it's not flipped versus when it is flipped.
Dack is really good, but I find myself wondering if a Red Splash is worth it. Red does give us some of the best spells in the format against Workshops, while black gives us great spells against Dredge, and Blue has great spells available against other blue decks. Overall, my question is, is Dack good enough with only 2 or 3 moxes, lotus, and Lotus Petal? Dack does assist our Doomsday Piles, which is always nice.
If Dack's mana cost was a concern, JTMS is a worse concern. However, this card undoubtably win's the game.
I played this before, in 2010 when Gush was restricted the 2nd time around. That list can be referenced at the bottom of this post. However, there is no way I play Meditate in the current iteration of this deck, in the current iteration of this format.
I have considered playing this card as another cantrip - Either this or Peek. Peek is nice as it gives information that we can use on our opponent's end step in advance to setting up our Critical Turn. I just really like Opt's new art.
This card is a great one at it filters our mana to get to Doomsday, and more importantly, it is a mana source, and drawing the card is attached to that mana source, so if you resolve Laboratory Maniac with 1 mana open and 0 cards in your Library, you win the game regardless how many ways your opponent could otherwise remove the Maniac. I did this on stream to beat a Dismember the day Gush/Probe were restricted on MTGO, and it felt FREAKING FANTASTIC.
How do you keep up with the Workshop decks?
I was really a fan of Pithing Needle in my Snapcaster deck, to the point where I will be playing this card (Again) in Doomsday's Sideboard. In the past, we named Wasteland so we could use Ingot Chewers to extend through Spheres, but right now I worry more about them racing us or having Ravager+Ballista making losing half our life a really big deal. Pithing Needle on Ravager and/or Ballista is pretty good, and the card also does well vs Dredge.
What is the best way to beat the Dredge Decks?
I found Yixlid Jailer is really good, but getting to 1B when you're not playing full power is difficult. Another card I'm a HUGE fan of is Planar Void - It's one of those gems from back in the day that's really good, but it is still Misstepped. Note it's a trigger, not a replacement effect, so you/opponents can still do things like 'Ancestral,Trigger, respond Snapcaster Ancestral'. Pithing Needle is good here as well, and I might be tempted to even sideboard a Bojuka Bog.
Is Laboratory Maniac and Tendrils of Agony still the best win conditions?
I'm torn on Laboratory Maniac, but I think you need to keep it. Tendrils isn't actually a card I want to play - without Fastbond and Gushes you won't get the storm count + the Mana to successfully Tendrils someone. There are risks to not playing the Tendrils of Agony (if you don't replace it with a different win condition) - You cannot remove Laboratory Maniac to Force of Will otherwise you die immediately, Swords to Plowshares, Pyroblast, etc. all become a lot more risky for you, and you don't have a successful finisher after Yawgmoth's Will. These are all items I am working to rectify. Other options would be to go back to the Mind's Desire + Becon of Destruction Kill, which has it's own risks, or playing a Monastery Mentor, which I've done a lot of scenarios with to find a Doomsday stack that wins, or Tinker+Blightsteel which you can set up a Time Walk turn with Doomsday, but is mana intensive and requires you to play enough artifacts to support Tinker. Bottom line, there is a great win condition out there - we just need to find it.
Is Doomsday a combo or a control deck?
Doomsday is a control deck the same ways Gifts Ungiven was a control deck in the mid-2000's. You control the game until you cast your key spell and the game ends. As such, I recommend playing 1 Dark Ritual, because you can Mystical Tutor for it in a pinch. I also recommend playing a Merchant Scroll as it can find a counterspell or a Gush, and I recommend playing Vampiric Tutor and Demonic Tutor. One card I don't like playing, because I am already playing 2 top-of-the-deck tutors I am not a huge fan of, is Imperial Seal.
On top of that, I also suggest playing 2 to 3 Doomsday, but also playing a Treasure Cruise and a Dig Through Time.
Your deck should be designed to go off on turn 3 or 4, and Cruise and Dig both fire at around that time on average, and more than likely can draw you into a Doomsday or a way to get Doomsday. Having 4 Doomsdays always felt like to much even in 4 Gush days, and in the 1 Gush/1 Probe really limits our ways to fire a Doomsday on Turn 3 without too much risk.
Hopefully this is enough of a post to get discussion going.
Sidenote: WTF Soly with a very good post. I'm losing my edge.
Soly Doomsday from 2010: http://www.eternalcentral.com/xtreme-games-08-15-2010-top-8-decklists-coverage/