I still think bringing hydra back is a questionable move, but since hydras will be a thing again and The Magistrate helm is receiving a buff (all nova runes and more damage), maybe we could do something about Rimeheart and have a Frost Nova Hydra build (and not the fire one that used to cause lag several seasons ago).
Also having another strong option competing with Channeling items can’t be bad. I don’t know how the changes to Deathwish and Etched Sigil will affect non Bazooka builds, but I guess the lower tier builds will still be viable to some extent.
My suggestion is simple:
Frost hydra and Frost Nova deal xxxx% more damage to enemies already frozen.
*I’m not adding other cold skills such as Frozen Orb because DMO and Tal Rasha builds would stack Deathwish+Sigil+Rimeheart. Restricting it to just hydra and frost nova will at least force you to use Serpent Sparker, breaking the channeling items combo.
Give it a decent damage percent, high enough to compete with Deathwish/Sigil, but not too high to a point you are forced to compensate with a hidden low proc rate that will pigeonhole players into 5APS Archon/Reverse Archon builds (like you did with Manald Heal).
There’re many different ways of wording a new effect and as long as it doesn’t strengthen what we already have (channeling and Archon) anything can work.