Not tried it but probably something like:-
Which should always check if your target has DI on it. IF you are using MQ2Dannet there's probably a much cooler and reliable way to do it (but I haven't figured that out yet).
Code:
[Heals]
Heals1=Divine Imposition|100|Cond1
...
[KConditions]
Cond1=!${Target.Buff[Divine Imposition].ID}
Which should always check if your target has DI on it. IF you are using MQ2Dannet there's probably a much cooler and reliable way to do it (but I haven't figured that out yet).

