In mere moments, the tide of battle would be shifted, though at first, Eric would not realize this. He had been expecting traps; but he had not expected to have his natural energy gathering so abruptly cut off. What had cut it off you might ask? Why, the erection of the barrier, and the beginning of the chakra suppression.
Using senjutsu to suppress chakra, while effective, did have one small problem; it was senjutsu. A described earlier, at least one layer of Eric's barrier had the ability to absorb chakra, and the initial rush would immediately tip Eric off to the nature of what he was faced with.
Truly panicking, for the loss of his barrier would mean the end of him at this current juncture, the man would seemingly drop to the ground, hand slamming upon the scroll. Thought he barrier could absorb the chakra and use it to maintain its form, the significant amount of chakra presumably being exuded would pose an issue of capacity rather than capability.
Nonetheless, the moment his chakra tapped into his barrier, he removed the original size limits, which had been designed to preserve chakra usage. This would cause the barrier to instantly expand in size, spreading rapidly acros the ground and through the air in a 3 dimensional fashion akin to a tailed beast ball expanding. Of course, this end result would not be detonation, but continued expansion as long as it was greedily taking chakra from its oppressor.
The expansion would be rapid. The cube-like barrier would swiftly grow in size until either the flow of chakra stopped (and even then it would maintain its size and stabilize if Eric were to once again place size restrictions), the barrier itself were destroyed, or it physically had no more room to grow.
Some math is required to properly understand the situation that Eric is faced with. A pyramid with a width of 350 feet, a length of 350 feet, and a height of 350 feet, the volume of the pyramid is about 14,291,666.67 feet cubed presuming that the volume of a pyramid is found by multiplying the 3 dimensions together and then dividing by 3.
The initial volume of the barrier that Eric is using is about 150,000 times smaller than that at a measly 288 feet cubed. This means that while this barrier completely dwarfs Eric's, it also would consume far more energy to use and to maintain, no problem for the sphinx in using nature's energy.
However, this also means that an incredible amount of chakra resides within the volume of the pyramid, since it presumably suppresses everywhere within the barrier at an equal rate, with the only exception being the area where there is a pass holder. Since Eric's barrier can and does absorb chakra, both to maintain itself and to defuse attacks, then it can absorb this mass amount of chakra as it comes towards it. However, though the barrier has no stated limit, it would be nonsensical for it to be able to remain at the same size despite the large amount of chakra that it is absorbing.
By increasing in dimensions, the barrier uses up the chakra that it is absorbing as it operates. Because of this huge amount of chakra bearing down on it, the barrier would very swiftly have a strong and full source of chakra, expanding immensly fast after it is released from its size restraints. The barrier could theoretically expand into eternity, but the pyramid vs prism limit this possibility. Once it reaches a certain size, its dimensions are going to beyond some of the boundaries of the pyramid.
The volume of a pyramid is 3 times less than that of a standard rectangular prism, so the dimensions of the prism would be approximately 3 times smaller than that of the pyramid before it encompasses about the same volume (doing the actual math, the volume it can encompass, the prism, is a little greater, but the point has been made that the prism doesn't have to have the same dimensions as that of the pyramid in order to encompass the same volume (I.E, have the same area within it as the pyramid).
It would have to go beyond the surface area boundaries of the pyramid, so before having the same volume as the pyramid it would be more prone to actually breaking the pyramid barrier by absorbing some of it boundaries.
While all of this is going on, naturally, the battlefield is not going to be still. All the same, Eric's barrier, once able to expand with the amount of chakra it receives, would be capable of thus dealing with the effects of the opposing barrier with or without his foe dispelling it.
Back in character:
Eric would, upon letting loose his barrier to begin his fortune counter (for nothing else in his arsenal would have helped him in nearly the same way) he would still be connected to the barrier. Taking in some of the excess senjutsu, Eric would immediately enter sage mode. This "borrowing" of the chakra absorbed by the barrier would slow the barrier's growth considerably, but very shortly after recieving just enough to enter maximum sage mode, he would proceed. This would buy Ichirou another good 2 seconds to escape before the barrier completely rams into him, sending him to the shadow dimension and sapping at his chakra.
How could Eric possibly go into sage mode with another creature's senjutsu? Natural energy is a universal product, the only difference being in how it is gathered. Since all animals sense the world slightly differently, the differences between animal sage modes would largely be within how to gather natural energy on the personal level; how that energy is then used is also dependent on the creature.
Here, however, raw senjutsu was used in an attempt to suppress chakra, so it would be ripe for the picking. Once in sage mode, Eric could more easily detect his surroundings. He sprouted wings and claws, his skin became like a dragon's scale armor, and his eyes attained the trademark crimson shading and brille. Albeit, the brille were not down at this time, they were present.
All of his senses, strength, and general abilities were increased. The chakra he obtained from the sphinx would of course add to his overall pool, restoring him ever closer to 100% (100% if he were to get the chance to enter "full" sage mode).
If Ichirou had his creature stop the barrier early (which he would be very prone to do once he understood that it was doing more harm than good) then while Eric could still go into sage mode (as the chakra suppression of the area of the pyramid would still be present even if the barrier itself is removed, unless said senjutsu were also re-absorbed. Even then, the initial pressure plus the small amount of natural energy gathered would be enough to enter sage mode, albeit, not with nearly as much senjutsu to work with for the remainder of the fight.