The formula at level 15 is:
Block: +(STR + CharLv × 3 + 675)
Assuming you are at level 200 with 200 STR, that will give you 1475 block.
Assuming you are at level 300 with 300 STR, that will give you 1875 block.
Meanwhile Peltasta’s High Guard at level 15 gives you this:
Block: +240
Attack: -50%
Critical Chance: -100
So when is Peltasta going to get fixed? Or are we going to start tanking with a 2H sword as a Highlander now?