Cause of the influx of Karma- One of the nine Tattvas (categories of truth);
that state of the soul, which becomes the cause of the attraction of Karma-pudgalas (material clusters qua Karma).
karmākarṣaṇahetnrātmapariṇāma āśravaḥ.
...āśravanti- praviśanti karmaṇi ātmani yena pariṇāmena sa āśravaḥ karmabandhaheturiti bhāvaḥ.
(Jaisidī 4.16 Vṛ)