You have the payoff but too few ways to activate it.
Look for Dissection Practice.
Practice targets a creature and triggers Scornmage before resolving. Its life gain can also bridge into infusion effects.
Your synergy is already working but you keep falling behind.
Take an early play or answer before another expensive reward.
A pile of tricks needs enough creatures. Repartee does not trigger from an activated ability or an Aura spell.
The support is missing
Favor castable creatures and interaction if narrow support does not arrive.