atsteigan

[← at- pref + steigan v “to climb (up), mount, ascend”]

atsteigiþ - 3 pers, sing, pres, indicat - Thessal. I, IV, 16
atsteigai - 3 pers, sing, pres, optat - Luk. XVII, 31
atsteig - 2 pers, sing, imper - Mrk. XV, 30; Luk. XIX, 5
atsteigadau - 3 pers, sing, imper - Matth. XXVII, 42; Mrk. XV, 32
atstaig - 3 pers, sing, p, indicat - Luk. XIX, 6; Jhn. VI, 33; VI, 38; VI, 42, VI, 50; VI, 58 etc
atsteigands - pres.p.- Matth. IX, 1; Jhn. VI, 41

4.1.1.1. (a)

I class	infinitive	preterite singular	preterite plural	past participle
	normal grade	normal grade	zero grade	zero grade
i/ă	-i-	-a-	zero	zero
additional element of vowel gradation for this class is [-i-]	i + i = ii [ī]	a + i = ai	zero + i = ĭ	zero + i = ĭ
to grab, grasp, grip	greipan	graip	gripum	gripans
to show; to tell, announce	teihan [-i:-]	taih [-ai-]	taihum [-ɛ-]	taihans [-ɛ-]

See the complete paradigm of the conjugation of strong verbs