Weaknesses:
Lack of Combat Ability - If you play against an aggressive combat deck,
especially a recycling regent deck (with Regents (no instant killer champ),
and Staff of Conjuring, Armor of the High King and Tas to recycle used
combat cards) you can sometimes get swamped before you can slow them down
enough.
Immune
Realms - Risk minimized though Iuz razing immune realms (then destroy
when they're powerless) and getting the realm before played through Monte,
Ren's CB, Tarokka, Storms at Sea etc).
Vulnerability
to Anti-Majic Rules - Nullify Magic, Forbidden Knowledge and Antimagic
Cloud can cripple this deck. Possibly adding another rule would help.
Vulnerable
to Negation Decks - Decks with recyclable negations can stop this deck
being effective. An example might be Tas/Amulet of Dispel Magic negates
1 spell/turn. Add in Bigby for a turning and The Last Sea for a rebuildable
realm turning and the offensive spells are in trouble. Combine with
all the event negaters (Limited Wish, Helm, Delsenora, Intercession, and
the Medusa Throne) and this deck loses most of it's focus.
Vulnerable to Spell Stopping - Deck becomes
pretty weak if it can't cast spells. The Dungeon protects this, and
the non-mages stop normal Midnight, but is a little vulnerable to anti-
dungeon cards with the avatar Midnight or Icon of Magic. If you're
getting hit by these regularly, would pay to include Hornung the Anarch
and some champion killers like Assassins and Talcon (4th/341).
Vulnerable to Its Own Combos - A smart
opponent might be able to stop this deck by turning the combos used against
the deck by stopping them halfway (which is less likely if you can see
their hand). For example, the Monte and Storms at Seas combos give
the opponent their realms on top of their deck first (through Espionage,
Yagno, etc). If they stop the combo halfway, they've got ample realms
immediately and lessen your chance of stopping them in time!
Poor in Multiplayer - The best thing with this deck is to hammer one
opponent down, keep them pool-less until they can't possibly win due to
lack of realms outside the Abyss. Against 2+ opponents though, there
are too many Realms to destroy for this to work well – focusing on 1 opponent
means the other guy will have a pool and probably win, and splitting between
them often won't cripple either or delay them enough for you to win.
And all your realms will be
razed near the start as you can't fight head
to head against combat decks. It can still win if you turn it into a long
war of attrition, but you need to be very careful playing opponents against
each other, not fighting unwinable defences (even preferring to have no
unrazed realms) and wary of opponents, especially saving counter cards.
You should substitute in Siege and Tarrasque at least to affect multiple
players.