MobTalon
Villager
A bit late, but yes, it's perfectly legal (and RAI) that Eldritch Strike gives disadvantage on saving throws against spells you cast (past-tense) before the end of your next turn.
The key is "that creature has disadvantage on the next saving throw it makes against a spell you cast before the end of your next turn" to be read as "that creature has disadvantage on the next saving throw it makes (...) before the end of your next turn". The "against a spell you cast" is a qualifier to indicate that only your spells have this effect. And "cast" is a irregular verb that is written "cast" in the past tense.
The key is "that creature has disadvantage on the next saving throw it makes against a spell you cast before the end of your next turn" to be read as "that creature has disadvantage on the next saving throw it makes (...) before the end of your next turn". The "against a spell you cast" is a qualifier to indicate that only your spells have this effect. And "cast" is a irregular verb that is written "cast" in the past tense.
