BlueBattle — Siege // Legendary Creature — SerpentInvasion of Segovia // Caetus, Sea Tyrant of Segovia
Mana value3Rank#5,442
The Commander
(As a Siege enters, choose an opponent to protect it. You and others can attack it. When it's defeated, exile it, then cast it transformed.)
When this Siege enters, create two 1/1 blue Kraken creature tokens with trample.
Noncreature spells you cast have convoke. (Your creatures can help cast those spells. Each creature you tap while casting a noncreature spell pays for 
or one mana of that creature's color.)
At the beginning of your end step, untap up to four target creatures.
Guide
Gameplan
Flip Invasion of Segovia into Caetus to make your creatures double as a mana engine, convoking out a flood of noncreature spells (counters, card draw, big finishers) while untapping up to four creatures each end step. You go wide with tokens, then leverage convoke to cast spells far ahead of curve and slam control over the late game.
Strengths
- Convoke on every noncreature spell turns a wide board into explosive ramp for counterspells, draw, and bombs
- End-step untap keeps blockers up and refuels your convoke pool for the next turn
- Comes down cheap as a 3-mana Siege that immediately makes two trampling Krakens
- Mono-blue gives access to the format's best card advantage and counter magic
Weaknesses
- The Battle must be defeated before you get Caetus, and opponents can choose not to attack it, slowing your plan
- Board wipes gut your convoke engine and leave you with no mana army
- Mono-blue struggles with permanent-based removal for resolved threats and enchantments
- Caetus himself is a vanilla 6/6 with no evasion or protection once flipped
Key Cards
- Caetus, Sea Tyrant of Segovia — The payoff: convoke on noncreature spells plus untapping four creatures each turn is the deck's whole engine.
Upgrade Path
Add more cheap, recurring token makers (Talrand, Murmuring Mystic, Young Pyromancer-style blue analogs, Brudiclad) so you always have convoke fodder, and load up on impactful noncreature spells that benefit most from being effectively free. Layer in untap synergies and mana doublers to abuse the end-step untap, and lean into a clean wincon like a big X-spell or an infinite-mana outlet to convert the engine into a finish.
Core Cards
The most-played cards for this commander, built from aggregated deck data (the Mythic Graph). Build public decks to seed it.
Win Conditions
- ▸Overwhelm with a wide Kraken/token board after convoke clears the path
- ▸Resolve a game-ending finisher like a huge X spell or Stroke of Genius mill
- ▸Grind to a controlling endgame and ride card advantage to victory
- ▸Convoke into a combo payoff for an explosive single-turn kill
Archetypes
- Tokens — Convoke rewards going wide, so token producers turn bodies into mana for your spells.
- Spellslinger — Cheap-to-convoke instants and sorceries chain together while your creatures stay untapped for blocking.
- Control — Free-ish counterspells and card draw via convoke let you hold up answers without committing real mana.
- Big Mana Combo — Untap effects plus convoke can power out and reuse expensive spells far ahead of curve.
Combos
- Jeskai Ascendancy + Invasion of Segovia // Caetus, Sea Tyrant of Segovia
→ Infinite storm count, Infinite self-discard triggers, Infinite untap of creatures you control
- Stormsplitter + Invasion of Segovia // Caetus, Sea Tyrant of Segovia + Haze of Rage
→ Infinite LTB, Infinite ETB, Infinite storm count
- Stormsplitter + Invasion of Segovia // Caetus, Sea Tyrant of Segovia + Reiterate
→ Infinite LTB, Infinite ETB, Infinite storm count
- Invasion of Segovia // Caetus, Sea Tyrant of Segovia + Intruder Alarm + Recruit the Worthy
→ Infinite creature tokens, Infinite ETB, Infinite magecraft triggers
- Stormsplitter + Invasion of Segovia // Caetus, Sea Tyrant of Segovia + Searing Touch
→ Infinite LTB, Infinite ETB, Infinite damage
Combos via Commander Spellbook.
Related Commanders
Same color identity (U), by popularity.
