Your damaging cantrips affect even creatures that avoid the brunt of the effect. When you cast a cantrip at a creature and you miss with the attack roll or the target succeeds on a saving throw against the cantrip, the target takes half the cantrip’s damage (if any) but suffers no additional effect from the cantrip.
RollQuest ships the D&D 2024 SRD as a content pack, on a 5e character sheet that does the maths - roll from the sheet and let the numbers work themselves out. Free to start.