Here you go...
Round 5:
Malek takes out a torch (free) and flint/steel (use an object).
Hjalman uses his attack to disarm Vecna, rolling 1,3+10= 13 vs. Vecna DEX (Acrobatic) 2+3 = 5. He uses his free intereaction to pick up the dagger.
Egar disengages and steps back 5 feet.
Vecna attempts to escape the grapples. He rolls totals of 16 and 7 vs. Hjalman's 21 and Leon's 19, failing against both.
Leon moves south of Vecna and attacks twice with his IDS/sword.
He rolls 8,9+9 = 18 and 20,10+9 = 29 (CRIT), for 1 and 6 radiant damage.
Round 6:
Malek uses his action to light his torch.
Hjalman tosses Afterthought to Egar (free) and uses his action to light his torch.
Egar picks up the dagger and taunts Vecna with it, laughing.
Vecna attempts to escape the grapples. He rolls totals of 15 and 19 vs. Hjalman's 27 and Leon's 18, escaping Leon's grasp but still grappled by Hjalman.
Leon uses his attack to grapple again (20 total vs. Vecna's 7). He attacks with his IDS/sword, missing (totals 14 and 17).
Round 7:
Malek attacks with his burning torch, missing (8 and 13).
Hjalman attacks with his burning torch, missing (5 and 12) and then hitting (20 and 17) for 1 fire damage.
Egar takes watches intently.
Vecna attempts to escape the grapples. He rolls totals of 16 and 7 vs. Hjalman's 10 and Leon's 13, escaping Hjalman's grasp but still grappled by Leon.
Leon attacks twice with IDS/sword, hitting (21,28) once and missing (13,11) once, dealing 7 radiant damage.
Round 8:
Malek attacks with his burning torch, missing (17 and 3).
Hjalman hits (16,24 CRIT and 15,19) twice, for 3 fire damage.
Egar takes watches intently.
Vecna rolls to escape grapple (4,23) vs. (19,28), failing both.
Leon attacks, hitting once (19,25) and missing once (14,13), dealing 7 radiant damage again.
Round 9:
Malek attacks with his burning torch, hitting (20,16) for 2 fire damage.
Hjalman misses once (7,6) and hits once (17,21) for 1 fire damage.
Egar takes watches intently.
Vecna rolls to escape grapple (20,17) vs. (25,20), failing both.
Leon attacks, hitting twice (23,25 and 11,22), dealing 13 radiant damage.
Round 10:
Malek attacks with his burning torch, hitting (8,18) for 1 fire damage.
Hjalman hits once (20,19) and misses once (7,13) for 1 fire damage.
Egar takes watches intently.
Vecna rolls to escape grapple (21,21) vs. (26,23), failing both.
Leon attacks, hitting (18,22) and missing (16,11), dealing 6 radiant damage.
Round 11:
Malek attacks with his burning torch, missing (9,2).
Hjalman hits twice (18,8 and 22,18) for 2 fire damage.
Egar takes watches intently.
Vecna rolls to escape grapple (4,15) vs. (27,26), failing both.
Leon attacks, hitting twice (26,19 and 12,23), dealing 11 radiant damage.
Round 12:
Malek attacks with his burning torch, missing (11,2).
Hjalman misses twice (12,15 and 17,15).
Egar takes watches intently.
Vecna rolls to escape grapple (6,10) vs. (28,29), failing both.
Leon attacks, hitting twice (20,21 and 18,26), dealing 8 radiant damage.
Round 13:
Malek attacks with his burning torch, hitting (18,8) for 1 fire damage.
Hjalman hits (20,6) and misses (10,9), for 1 fire damage.
Egar takes watches intently.
Vecna rolls to escape grapple (7,17) vs. (29,19), failing both.
Leon attacks, hitting twice (28,23 and 28,15), dealing 8 radiant damage.
Round 14:
Malek attacks with his burning torch, missing (4,2).
Hjalman misses twice (14,4 and 6,15).
Egar takes watches intently.
Vecna rolls to escape grapple (9,23) vs. (13,19), escaping from Leon's grasp.
Leon fails to grapple twice! (10 vs. Vecna's 18 and 12 vs. Vecna' 18).
Round 15:
Malek fails to grapple (14 vs. Vecna's 14).
Hjalman hits twice (22,13 and 12,21), dealing 2 fire damage.
Egar takes watches intently, getting ready to cast again if Vecna escapes.
Vecna rolls to escape grapple (13) vs. (16), as Hjalman barely holds him down! Vecna curses!!
Leon grapples again (29 vs. Vecna's 21), and attacks with his IDS/sword, hitting (16,27) for 7 radiant damage.
Round 16:
Malek attacks with his burning torch, missing (5,6).
Hjalman misses twice (13,5 and 17,11) with his torch.
Egar takes watches intently.
Vecna rolls to escape grapple (5,9) vs. (22,23), failing both.
Leon misses (11,13) and hits (11,18), dealing 8 radiant damage.
Round 17:
Malek attacks with his burning torch, missing (11,15).
Hjalman misses twice (9,14 and 14,14) with his torch.
Egar takes watches intently.
Vecna rolls to escape grapple (11,4) vs. (21,20), failing both.
Leon hits twice (21,16 and 25,25), dealing 5 radiant damage.
Round 18:
Malek attacks with his burning torch, missing (5,9).
Hjalman hits (20,6) and misses (7,4), dealing 1 fire damage.
Egar takes watches intently.
Vecna rolls to escape grapple (22,22) vs. (27,11), escaping from Leon again!
Leon grapples (23 vs. Vecna's 12) and attacks with his IDS/sword, missing (13,12).
Round 19:
Malek attacks with his burning torch, missing (13,5).
Hjalman hits (21,16) and misses (8,9), dealing 1 fire damage.
Egar takes watches intently.
Vecna rolls to escape grapple (4,22) vs. (13,26), failing both.
Leon hits twice (28,18 and 12,23), dealing 5 radiant damage!!!
VECNA IS DEFEATED!!!