You must prioritize wave control to prevent Ashe from walking you down with slows.
Maintaining health lead through superior range and stacking Seraphine R with Ezreal's burst.
Getting isolated by Ashe slows or being caught by Sona's level 6 flash-engage without flash.
Respect Ashe Level 2 Shove
Do not walk past minion wave for poke
Track Sona's Flash cooldown constantly
Save W for disengage only
Ashe wants to slow you to 0 and let Sona scale until their utility out-values yours.
Level 6 and late-game teamfights where Sona's low cooldowns provide infinite sustain.
Avoid long trades. Use your range to poke Sona down to 40% HP so she cannot safely walk up to poke.
Summon Aery for consistent poke and shielding; Manaflow Band is non-negotiable for lane sustain.
Max Q for waveclear and poke, then E for longer CC duration. One point in W early is sufficient.
Rylai's Crystal Scepter is core; it turns your E into an instant root, making it impossible for Ashe to kite.