The affix ṭhak comes after a word in the Instrumental -3rd case in construction in the sense of 'he plays', 'he digs', 'he conquers' or 'he is conquered'.,
Thus अक्षैर्दीव्यति = आक्षिकः 'who plays with dice -- a dicer'. शालाकिकः ॥ अभ्र्या खनति = आभ्रिकः, कौद्दालिकः, अक्षैर्जयति = आक्षिकः, अक्षैर्जितं = आक्षिकम् ॥ शालाकिकम् ॥
Though the rule is couched in universal terms, yet the affix does not come after every instrumental case. Thus देवदत्तेन जितम् will not give rise to any affix, for the word दैवदक्तिकः is not found in usage having this sense. So also अंगुल्या खनति gives rise to no affix. Though the verbs 'divyati' &c, are in the 3rd Person Present Tense, Singular number, the derivative is not limited by these conditions. Thus आक्षिकौ and आक्षिकाः what are also valid, and so also अक्षैरदीव्यत् will give also आक्षिकः; so also आक्षिकस्त्वम् आक्षकोहम् ॥ Though in a sentence the verb is generally the principal word (क्रियाप्रधान), here owing to the Taddhita affix, the instrument is taken as the principal.,