Seraphine and Miss Fortune can lock down enemies with their CC, and layer their ultimates to devastate enemies; let's break it down.
Overview: Laning Phase Synergy
Miss Fortune has a pretty safe laning phase. Her passive allows her to push waves quickly by frequently switching targets and makes it easy to last hit minions, while her E can be used to poke enemies or push waves. With the bonus movement speed granted by her W, Miss Fortune can dodge skillshots and escape jungle ganks or an engaging support. The most effective way to damage the enemy bot lane is to land the bounce from her Q, which is guaranteed to crit if the initial shot kills its target. Therefore, the best Qs will be used on low health minions that are just in front of the enemy bot lane, as it will kill the minion and bounce to crit the enemy.
Perfecting Seraphine requires constant awareness of her passive, which duplicates Seraphine’s next ability after she casts 2. This can be used to poke away at enemies with her Q, CC enemies with her E, or protect you and your ADC with your W. Preserving your passive is important as Seraphine has long cooldowns in the early game, so it’s important to have it available if you suspect a jungle gank is imminent or the enemy support is about to engage. A duplicated W is great for escaping ganks and engages thanks to the bonus movement speed and shield, while a duplicated E can prevent an engage from the enemy jungler or support.
Gameplay and Ability Synergy
Considering Seraphine’s E will root enemies that are slowed, Miss Fortune can use her E to slow the enemy bot lane before Seraphine follows up with her E to root them. Not only does this allow Miss Fortune to land a Q and basic attack (which will also be enhanced by her passive), but Seraphine doesn’t need to use her passive with her E to CC the enemy. Instead, she can use her passive with her Q on the rooted enemy to deal even more damage. Miss Fortune can also pop her W while the enemy is rooted to increase her attack speed and land more basic attacks.
Once this duo has reached level 6, their ultimates can be cast together for an incredibly powerful AoE combo. If Seraphine can land her ultimate to charm the enemy, Miss Fortune can immediately follow up with her ultimate to shred through enemies while they are CCd.
Best Runes and Items for Champion Synergy
Miss Fortune’s build is pretty flexible. She can take Arcane Comet which is incredibly easy to land with her E, or Press The Attack which can be procced with her Q and basic attacks after using her W to increase her attack speed. Her item build is equally as flexible, as she can take the standard ADC mythic of Kraken Slayer or opt for a lethality build with Eclipse. Regardless, you should always build Infinity Edge, The Collector, and Serylda’s Grudge.
Seraphine should take Guardian for the consistent protection it provides for you and your ADC, and Font of Life to heal allies whenever you land your E or ultimate. Moonstone Renewer is a fantastic item for Seraphine, as the bonus heal and shield power it provides means your W can heal and shield for an absurd amount in the late game. Other than that, Seraphine should build standard enchanter items like Chemtech Putrifier and Redemption.
Miss Fortune and Seraphine have a pretty safe laning phase thanks to the their long range and bonus movement speed, and can make consistently favourable trades by rooting enemies with their CC. Upon reaching the mid/late game, successfully layering their ultimates can single handedly win team fights.