Once the shadow seal technique began its suction, using the preta path on it would have been ineffective in nullifying the effects; the chakra barrier would not be able to get at the chakra backbone of the technique by the time the suction began, only the entry to the sealing dimension.
If Eric had been left unharassed, it would be case closed and cut for the clone. But such was not the case.
The fuinjutsu stopped working altogether! This was unexpected, to say the least, especially with the re-appearance of his foe, or at least the appearance of a previously not present set of hands.
Though he did not know specifically that his foe intended on sealing him (perhaps as a counter to the notion that Eric intended on sealing a clone of an Uzumaki, why this would be ironic likely to become evident by next post) he was aware of a suddenly appearing form near his lower half. How so? As earlier pointed out, the shadow sensory technique allowed Eric to sense things in the shadow; as earlier hinted, this was a touched based sensory. Air disturbance, movement, another's shadow, all fell under things that the man could sense with his shadow.
Therefore, the moment Rikudo became tangible once again and advanced even a millimeter further, he had temporarily given up the element of surprise, because natural wind/snow patterns are not naturally disrupted in such a manner without the intervention of another. Additionally, the movement would have been in the shape/motion of an extended hand, meaning that fingers as well as the fact that they were hands could be detected as well.
By extending his hands from the ground, had he been tangible, that would have immediately triggered a different response. However, Rikudo had cleverly remained intangible until mere centimeters from Eric, forcing Eric to rapidly change plans. He might would try his fuinjutsu again, but the man couldn't risk it failing at such a range.
Still taking advantage of the great shadow that covered the field, Eric would imbue the shadows near him with a specific command; to send out tendrils of shadow to bind the disturbance. The disturbance being Rikiryou's invisible, but in motion hands; when triggered, tendrils of shadow would attempt to bind and restrain his the hands from the exposed arm portions (if any) up to the wrist and knuckles, completely restricting his ability to move. Presuming his foe might would attempt to go intangible in order to get around this ditch defense, the trap would activate at any time the man returned to tangibility and attempted to touch him. Considering that Eric's shadow covered the entire battlefield, there would be no time between the trap's triggering and its execution at such close range.
(Kagemane: Kagewana; Shadow Imitation: Shadow trap)
This, combined with his forward running motion, was intended on stalling and buying time for his next maneuver. Since it was unlikely that the clone would stand idly by, even at the considerable distance, Eric needed to regain control of the situation, which had swiftly went from entirely under control to just barely graspable.
His next plan required the use of his fingers. Immediately after imbuing the command into the shadow around him, Eric would set to work manipulating yet more shadow, this time controlling it with his fingers. Likely idle due to the below-ground status of his attacker, Eric would use shadow tendrils near one of his weapons pouches, swiftly withdrawing a keepsake from the Jounin Exams.
(Kageyose no Jutsu; Shadow Gathering Technique)
A crystal, clear in color, would swiftly extend about an inch into the shape of a crystalline dagger before a red and yellow tint would emit from its base. This would happen upon the shadow grasping the crystal within the pouch, which would be nigh instant under the current circumstances. The "hilt", grasped by the shadow, would keep most of this tint concealed. Depending on how his quarry acted, Eric would do one of two things:
This relies on the idea that his previous actions had at least bought him about one second's worth of time (perhaps a little less, since Eric did not have to use his own hands to reach into the weapons pouch plus he moved physically to try to get out of reach of the hands). If his opponent had found a way to continue attacking him, then Eric would activate the yellow crystal upon his foe once again materializing. The effect would be to extend a bubble shaped barrier with a range of about 30 yards all around (so a 30 yard diameter) that would surely cover his opponent and himself within it. The bubble would disrupt all chakra within the barrier's reach, including that of Eric's shadow imitation.
Since Eric's shadow imitation takes chakra, then it (including the shadow trap) would be disrupted, potentially along with all of the jutsu augmenting Rikiryou (the barrier, potentially Kamui, hiding with camo, potentially Mind's Eye technique, and the fuinjutsu). This would leave a temporary zone where chakra-requiring jutsu (excluding the crystal) would be useless. Of course, since shadow imitation is what Eric had used to hold the small crystal dagger in the first place, then the dagger would threaten to fall (to which Eric would respond to next turn). However, needing only chakra to activate the crystal's effects, the crystal would draw on Eric's chakra noticeably upon activation.
Yellow Crystal- Disrupt chakra (Activated)
Hence, Eric would refrain from activating the yellow crystal as of yet and instead bring the crystal dagger to his open right hand if Rikiryou was stopped and/or retreated, as determined by his shadow imitation sensing.
The latter, while preferable for chakra preservation, could not quite top the potential danger to Rikiryou should the former happen. Without intangibility (among other things) Rikiryou would likely suddenly become of the earth, restrained if not killed by the ground that he had previously been using as cover. More importantly, it would put him more on edge, and less likely to attempt another attack of this sort again in the future; surely a plus for Eric's health one might add.