Kayle & Nami Synergy
Kayle Top and Nami Support win 56.2% of 1,516 Low Elo games together, +1.9 points vs expected, 2-patch window 26.19-26.20.
Researched on LoL patch 26.20. Tips are written to hold at any rank; stats come from Low Elo ranked games up to patch 26.20.
Why this duo works
Nami adds sustain, speed and protection to help Kayle reach her later range and damage, while Kayle's ultimate can protect Nami or another carry during a dive. Kayle players also value an enchanter alongside her scaling damage.
Playing the duo
Nami's Tidecaller's Blessing(E) adds damage and a slow to Kayle's attacks and spells, while Kayle's Divine Judgment(R) can make an allied champion invulnerable.
How to play as Kayle
Use Divine Judgment(R) to protect Nami or the main damage dealer when a diver commits; the invulnerability gives your team time to turn the fight.
How to play as Nami
Use E on Kayle when she is ready to trade or deal sustained damage, and keep W available to help her survive the weaker part of the game.
Sources
These notes come from r/Kaylemains, checked against the champions' abilities.