Straight up, an invoker should never get blackjacked. A thief has to get extremely lucky to do so. There is no reason you should be sitting on a road with a thief about without rain of stones ticking. If you are on a road you are standing still with a trap rdy to insta pwn any thief that shows up. Plus arials limit you on your travels, the underwater vuln is just to much to deal with imo. It limits you on some of your best places to set up ganks and explore. Granted volkov was not in a cabal so I didn't have to raid empire/tribunal, but other than having to raid empire/tribunal there is no reason to pick a race solely for blackjack as an invoker. If a thief is pissing you off, sit on eastern road or that road outside the inn with a pit/quicksand and rain of stones running and you'll snag the kill. Just gotta be patient. You'll get them atleast once thinking they spotted an easy target.