This has come up before and I've always liked it. I like your option 2 - a separate ability to double potency and halve duration of party-target recovery over time spells. I'd like it to work not only on Regen but also Adloquium. In addition, it could work on animus spells if they were first changed to be enmity reduction and increase over time.

This should not miss, it should be non-stackable and the recast should be such that it can be maintained on just one or two people simultaneously.