Tarn is just 25pts of stupidly-hard-to-kill when paired with an R7 Astromech. Every time someone attacks you, you can make them reroll any dice that you want, which happens before they are allowed to reroll from target locks etc. Since a dice can only be rerolled once, that means the attacker is forced to use Focus and little else, after his hits and eyeballs have already been rerolled once. Strap on a Shield/Hull upgrade and watch Tarn live pretty much forever.
Heh, that sounds pretty funky