Very briefly and simply:

1. When does a jīva feel like taking dīkṣā?

- The deep urge for renunciation (saṃvega, vairāgya) arises when mohaniya karma – especially charitra‑mohaniya – becomes weak (kṣayopśama) and samyaktva is somewhat stable. - So yes, the feeling “I must leave saṃsār and take dīkṣā” is a result of udaya + kṣayopśama of the right karmas: - mithyātva / darśan‑mohaniya gets suppressed/destroyed → samyak darśan - strong kaṣāyas of charitra‑mohaniya get softened → intense vairāgya and saṃvega.

1. Is it only kṣayopśama of charitra‑mohaniya?

- Not only. For real dīkṣā‑bhāva, both are involved: - some level of darśan‑mohaniya subsiding/destroying → right faith in Tīrthaṅkara, guru, śāstra. - significant weakening (kṣayopśama) of charitra‑mohaniya → control over passions so that great vows seem possible and sweet, not burdensome.

1. What about abhavya jīvas taking dīkṣā?

- Abhavya = a soul that will never attain mokṣa in the infinite future. - Even an abhavya can: - take external dīkṣā, - practice restraints to some extent, - and therefore have temporary kṣayopśama of charitra‑mohaniya (passions cool down for some time). - But: - Their mohaniya is never destroyed from the root in the perfect way needed for mokṣa. - So they may take dīkṣā, fall back, again rise, but the ultimate total kṣaya of mohaniya leading to keval‑jñān will never happen for an abhavya jīva.

1. So the key distinction:

- Bhavya jīva taking dīkṣā: - kṣayopśama now can gradually lead, over lifetimes, to real kṣaya of mohaniya and finally mokṣa. - Abhavya jīva taking dīkṣā: - also experiences kṣayopśama of charitra‑mohaniya, enough to support dīkṣā‑life and some śubha‑charitra, - but never reaches that final, absolute kṣaya by which mohaniya is finished forever.

So:

• Yes, dīkṣā‑bhāva is closely linked with kṣayopśama of charitra‑mohaniya (along with darśan‑mohaniya).
• Abhavya jīvas too can have such kṣayopśama and therefore can take dīkṣā, but their mohaniya never gets totally destroyed in the ultimate sense, so mokṣa does not come to them.

If you want to read a simple overview of mohaniya karma and its types, you can see this explanation here: Mohaniya karma (deluding karma)