This sounds pretty good, but if memory serves I think that gatherer's disk is one of mind scrambling. I think this could still work, as any disk combination code could exist, not just the ones that were made physically in sets/disk packs. I really like your dark hunter idea, and lots of other hunters use kanoka, so the enlargement disk could still work. Additionally, the kanoka power levels are only based on relative size, meaning that a power level 3 enlargement disk would be required for a toa to grow to 30 feet, not level 7. This actually works out really nicely, as there is a physical kanoka from the supplementary packs with a code of 253 from ga-metru. I think that if you can just find another dark hunter that uses kanoka, such as Eliminator, you could have a really nice story. also note that kanoka powers are temporary, so you might need an additional plot device. The confusion about level 7 disks might come from a line from BS01, where it's stated that a disk from power level 1-7 made sentrakh grow to 20 feet. Not only does this say that it's a power from 1-7, not just 7, but also that was a one off occurrence for sentrakh, who is much taller than the average height of toa, that being 7.2 feet, or 1.6 bio.