The idea behind this is very simple. Put cards into the graveyard quickly to activate Delirium. I have found that Vessel of Nascency will often activate it on its own.
Prey Upon is one of my favourites, it counts as a sorcery and can use it to take out fliers or anything problematic by using Gnarlwood Dryad as a target.
For an Instant I chose Grapple with the Past. It complements Vessel of Nascency quite nicely but also will allow me to bring back any creature from the graveyard that Vessel of Nascency missed.
For my Artifact I could only see Skeleton Key as being useful. It allows my weak creatures to attack directly and will also self mill. I decided to combine this with Asylum Visitor because it gives me agency of choice in which cards to keep at the beginning of my upkeep and which would be best to discard. It also works nicely with Obsessive Skinner who can remain as a Skulk 1/1 whilst building up stronger creatures.
I decided it was less useful to have 4 Asylum Visitors than other creatures as only 1 is needed once the hand is empty so I dropped it to 3 for 1 Ishkanah, Grafwidow
I also found Skeleton Key is less important so I swapped 1 for Liliana, the Last Hope which counts as a Planeswalker for Delirium.
Because self milling for Delirium naturally builds a large graveyard I put in Liliana's Elite. He can become very strong quite quickly.
From there I added bigger creatures with Delirium effects to round things off and 2 Ever Afters to fill the playing field. This is the bit I need some help with. Please let me know what creatures I could change to improve the deck.
Some of the cards I think would work as my big bads:
Mindwrack Demon Flying and Trample, and sends 4 to the graveyard when played. This would be a failsafe that also makes sure Delirium is turned on and also buff Liliana's Elite.
Soul Swallower Slightly smaller, but significantly grows in power every turn and has trample.
Ishkanah, Grafwidow When played it also adds 3 spider Tokens and can attack life directly.
Other small creatures with Delirium I could work in
Tooth Collector This gives 1 creature -1/-1 until the end of the turn, every turn. In the end I chose Obsessive Skinner over it because the effects are cumulative but I'm still thinking about using it.
Inexorable Blob When it attacks it adds another 3/3 Blob to the field. If I were to buff it with Obsessive Skinner this could make it hard to remove. And provide a constant influx of creatures.
