I believe this card should be a duo - preferentially with
. Water has already a lot of possible duos with
(mind flayer), with
(puffer fish), with
(trident), with
(spirit), with
(steam machine) and with
(chrysaora). Are left
and
.
I can agree that in there
is the only healing element. However, it seems too obvious to make it a
card. Light has so many healing ways that it is almost redundant. Also
has already a lot of permanent (8 - which is the highest number - ex aequo with
). In the remaining non-duo element I don't see any which would make sense in term of poison removal.
However, I think this mechanic could well apply to earth the combination of
and
could well give a nice therapeutic synergy. Trident being a weapon it would not make the duo too strong IMO. Also Earth has only 5 permanents (which is the lowest number - ex aequo with fire and entropy).
In summary, I would make this card a
permanent with a
ability.