Due too the design and making the main two single target abilities (Oblit and Frost Strike) cleave with D&D and Shatter Frost we aren’t left with many single target abilities that don’t contribute to cleave in some way.
Rime (disregarding avalanche talent) might be our only “big” ability that is purely single target. This alone can be buffed and honestly deserves is one capstone. Hopefully not one that just makes it cleave…
Inexorable assault is a MUCH MUCH weaker variant of Artic assault. Which it should be since its not a capstone. But its currently pure single target and does half the damage of GA from Artic assault.
The Razorice runeforge is prolly the biggest missed opportunity for pure single target damage. We now have HUGE attack speed buffs for IDT to proc and AOE but even with this attack speed the on hit damage from razor ice is .5% of our damage and pure single target baby.
A more detailed approach that would require more thought is to nerf the cleave mechanics and buff the single target abilities. Make D&D duplicate 80% of Oblit then buff Oblit so the cleave is about the same but more single. Nerf shatter but buff Frost Strike.