Before using Devour, Simon had previously considered consuming the Fleshwood's heart resin the normal way instead of using Devour.
If he consumed the Fleshwood's heart resin the normal way, it's guaranteed that he would obtain physical regeneration, mental energy recovery, and soul regeneration.
However, if he used Devour, it's not guaranteed that he would obtain all these three abilities.
And even if he did, there was the problem of him being only able to possess four more skills.
He had asked himself this question before using Devour.
'Would these three skills take up three slots of his Seven Stars Blessing? Or would he have to find a way to combine the three abilities into a single skill?'
Simon's proficiency with Devour had increased in the past two months, but it was not a drastic increase since he never used Devour on the corpse of a demon or demonic beast.
