This card is rediculous strong. My friend tested for the first time in his Leo deck in our Guardian of the Abyss first scenario and he managed to soak all the damage from monsters and treacheries. With the Wish Eater token cancel, he could pull all the attacks successfully, even when the abyss level became 5 or 6. We played with the Forgotter Age punishing chaos bag (we are at the last scenario in this campaign) and we won really hard. This card is essential to all tankie characters and IMO is a game changer. Also, with the swarming mechanic in Dream Eater, Empty Vessel becomes more strong, even one of the greatest cards for Guardias who have low sanity.
Abandoned by the Gods
Item. Relic. Blessed.
Limit 1 per deck. Uses (0 charges).
After you defeat an enemy: Place 1 charge on Empty Vessel.
If there are at least 3 charges on Empty Vessel: Search your bonded cards for Wish Eater and swap it with Empty Vessel, moving all charges from Empty Vessel to Wish Eater.
This one seems to be a very interesting card for Guardians since defeating enemies is basically what they do, but this card has a catch to it. Of current guardians, all but Carolyn Fern are able to take this card. A pity for Carolyn Fern, since it is the bonded card, not this card that heals horror.
For Leo, Mark and Roland this card has to compete with the always powerful Police Badge and the potential Police Badge/Well Prepared combo with one additional icon compared to this card. It also has to compete with the strong Hallowed Mirror. While also healing, the Hallowed Mirror does not cancel an icon from the chaos bag but does not need charges and does not cost any xp, so I think I would prefer the Hallowed Mirror over this card because of this. With Zoey Samaras, this card competes with one of the strongest investigator-specific cards in the game which is of course Zoey's Cross with an obvious outcome.
Of non guardian investigators Ursula is able to take this card currently (Father Mateo can take blessed only up to level 3), but she is very bad at defeating enemies with her 1 so she is not the obvious investigator to charge this card.
There is just one investigator I think of, when looking at this card, and this is (it might be a big suprise so tension is rising): Akachi Onyele - she can take "uses: charges" cards up to level 4. She does not really require the Holy Rosary because of her powerful stat and she definitly is able to kill monsters and she really like cancellation of special symbols for her spells and she starts this card with 1 charge and also can charge it with tokens. Akachi Onyele is a very potent monster slayer for a non Guardian so it might be worth a shot.
As a conclusion the most obvious investigator for this lv. 4 guardian card might be: A Mystic.
Manicly good and a natural supplement/upgrade to Hallowed Mirror. Requires some build-around.
Getting the charges is a bit of work, but is'nt a terrible challenge for a focused combatant character (like characters usually are). Once the charges are ready the ability to negate very bad tokens makes the character better at literally everything! In one go you can resist a treachery and heal pain, prevent a missed attack and heal, safely pull up a clue and -heal-!
When the Empty Vessel is charged and you swap for Wish Eater it opens a big window of power where attacks get more accurate, tests and treacheries get easier to beat and your pain literally flies away. The benefits make the commitment worth it.
A little groundwork and item teck is required to make it easier to find the Empty Vessel early enough to get the charges, a friendly with a No Stone Unturned, a Tetsuo Mori. Generally the cards you need to make a Empty Vessel shine are good anyway.
Once the Empty Vessel is on the table and charged you need to carefully consider when to swap it. Some scenarios have enough enemies running around that you can get it transformed twice, other times you would save up 3 or 4 charges to do the one and only swap of the scenario. Do note that the swap trigger is Fast and not locked into your turn, so you can rest easy with 3+ charges until right when you need the help.
Finally: Akachi Onyele can use it and it, works, gooood for her. She really needs Relic Hunter to make it work but oh BOY, a combat specialized Akachi Onyele with Wish Eater can bulldoze through fights.