FOUR SEVENS, ONE QUESTION

Mulligan for enablers, not for payoffs. The structural reason is in the decklist: 26 of the 99 are not legendary and are therefore invisible to Sisay forever - including three of the six cards that can pay her activation (Bloom Tender, Faeburrow Elder, Relic of Legends), all six counterspells, and all four Game Changers. She finds payoffs. She does not find fuel or protection. A hand holding Sisay and three expensive legends is a hand of payoffs and it does nothing until you draw the enabler yourself.

The seeded model keeps 84.2% of first sevens on a simple two-to-five lands rule, and mulligans a mean of 0.183 times per game - so the numbers say your opening hands are usually fine on lands and the judgement is entirely about colour and fuel. Three things make a keep. First, two to four lands with at least one unrestricted colour source: Command Tower, City of Brass, Mana Confluence, Exotic Orchard, Plaza of Heroes, Forbidden Orchard, a fetch land, or Secluded Courtyard on Human. Second, something that pays or accelerates - Birds of Paradise, Bloom Tender, Faeburrow Elder, Arcane Signet, Fellwar Stone, Relic of Legends. An early accelerant is in hand 63.8% of the time by turn six at a mean of turn 2.8, so a hand without one is not unlucky - it is below curve. Third, and best of all, a cheap two-colour legend: Katilda, Kinnan, Lotho, Saffi, Kambal or Kutzil each buy two ladder rungs for two or three mana, and Derevi buys three for three.

Ship the payoff hands. A seven with Jodah, Kenrith, Surrak, Samut or Jegantha and no fixing is four uncastable cards and a 2/2 commander whose gate reads 'mana value less than 2' - three legal targets, one of which is colourless. Ship the hand whose only acceleration is Sol Ring plus Delighted Halfling: both get Sisay onto the battlefield a turn early and neither can pay one pip of what she does there. Ship the seven counterspells-and-a-land draw, because your interaction is the half of the deck you can afford to draw into later. And be honest about the mana: five coloured pips with zero generic is a cost that sits off the end of the standard colour-source tables, so a hand with four lands that make three colours between them is a hand that casts your commander and then stares at her.

Two sequencing notes that belong in the mulligan decision. You are keeping toward the ladder's second rung, not toward a turn-three Sisay - the model already casts her by turn three in 8,028 of 10,000 games. And a cold-start activation is worse than it looks: at power 2 the three legal targets are Mox Amber, Mikaeus and Yoshimaru, of which Mox Amber is colourless and therefore steps the ladder not at all, and Mikaeus's behaviour when fetched rather than cast is an open question. Land a colour-diverse legend first, then activate.