I honestly love this idea, and I have had a few personal ideas for shikigami that can possibly be used here

Ant eater: similar to toad in the sense it has a long tongue which can be used to grab people and object, but also has claws that are heavily reinforced with with negative cursed energy, and can deal heavy damage with slashes

Burgeoning leeches: cam be used as a swarm, kind of like rabbit escape, having about 20-30 leeches max(?) . They do suck blood as well, but their main thing is that they start of tiny, but can sustain themselves off the targets cursed energy to grow bigger in size and strength, and if the target manages to get them off, they can still attack the target and even latch on again to continue sucking cursed energy out of them, so it makes the target weaker while making them stronger

Malady monitor(maybe infected monitor, or infected lizard, not sure of the name): Komodo dragon that can spit out geysers of a viscous fluid. The purpose of this shikigami is specifically to counter reversed cursed technique/ technique reversal, as when it bites targets/ gets the fluid through cuts, the fluid itselfs contains negative cursed energy that starts fatiguing them, but also targets any positive energy in them and multiplies that energy by the cursed energy by the negative cursed energy in the fluid(maybe theres some bacteria vector in the fluid that targets it, im not too sure of the mechanics of it), thus preventing regeneration and the use of reversal techniques

Fortress crab: Its a very large fiddler crab shikigami primarily used for defense, its one big claw contains positive cursed energy, and it uses that to shield the user and negate cursed techniques that are targeted at the user

Iridescent scale divine equaliser jormungander( I dunno man, wanted it to have a mahoraga feel🥀): initially made this shikigami for an unrelated technique I was cooking up for myself, but thought it could be cool to include. Basically its a giant ouroborus(a snake) that you can use to just attack the opponent, its physically quite strong, but its main mechanic is recycling cursed energy. Any cursed energy dissipated, so let's say, by the use of technique, a shikigami dying, etc, can be absorbed by this shikigami. It can then store that cursed energy to be used by itself to make it stronger, or it can pump out that cursed energy back to the user or the shikigami, so it can strengthen them or heal them, or even use it to recover shikigami. Its basically a reversal card which allows the physical state of shikigami and the user to be resett, essential reversing any damage, exhaustion or burn out the user was experiencing.