[@The 42nd Gecko]

Like I've said before, Henry can't store living matter in The Gates of Tartarus. To be more specific, nothing with intelligence sort of. Henry could theoretically shove a Machina into the Gates of Tartarus, but he would never do it for a few reasons. One it would Gove them full access to his horde of loot. Two it would really hurt Henry, like it would put him in the demon equivalent of a hospital for a few weeks at his current power level. Finally, he wouldn't be able to keep them in there, they could bust out with whatever they wanted to steal from him if the Machina was strong enough.