We'll, if he's criting on an 18-20, an avenger will crit 28% of the time, as stated by Iron Sky.
Now, with twin weapon fighting, that does become a 40% chance of getting one crit, and an 8% chance of getting 2 (for a total of a whopping 48% chance of critting). Again, as Iron Sky said.
Which really is pretty fantastic... making it a pretty good build no matter the strength of the avenger provided that the avenger hits the target with a roll of 18.
One needs to be a half-elf, though, which doesn't help the OP.
Incidentally, Darklord - any particular reason you want to go twin strike? Is if just for the gaming advantages of getting to reroll 2 attacks/round, or is there some additional reason?
Oi. 4e Bards are fine.Yeah, but you're a *bard*.
Yep.With Paragon MC, I lose Student of Caiphon or Radiant Servant, so I lose their crit ranges, right?
Oi. 4e Bards are fine.
You can get good DPR with just Avenger (Fighter) + Pit Fighter, because adding Wisdom again makes everything hurt more, and you hit quite often. Also, as a Fighter, you'll gain access to daily powers like Quicksilver Stance or Dancing Defense, both of which give you more attacks per round.
Advantage of paragon multiclass over paragon path:
You can chose your powers. Those powers are often more powerful than paragon path powers. You can take the paragon multiclassing feats.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.