I've searched the forum and my search didn't come up with a clarification. So my question is, the shooting attack of a troglodon is just one strength 5 hit right? Okay it causes multiple wounds but against a rank&file unit it would be almost useless right?
It's one strength 5 shot. It still has to roll to hit as normal. Yup, you are correct. The Troglodon is a complete and utter waste of points.
It could kinda work as a shooting decoy, but that only works if your opponent doesn't know how bad it is and then again it does cost alot of points for a decoy
Not that good as a shooting decoy either... large target and all. plus like you say, waaaaaay too expensive for the tactic. Use the points on chamo skinks and go war machine hunting!
For 15 points more you can pick up a Stegadon. The Stegadon is a much better shooting decoy, as it is more survivable. On top of that, the Stegadon can effectively fight in combat, is stubborn and has impact hits. The Troglodon has nothing on the Stegadon and they are nearly identical in terms of points cost. If for fluff/aesthetic reasons you really wanted to field a Troglodon (and realizing that it is still not going to be worth its points), I could see it used conjunction with: a hoard of Kroxigors (or two large units) and using the Trog's roar to get some additional S7 predatory fighter attacks on 5's and 6's Lord Kroak, for some Kroak bombing (skink priest with flight still works better though) Personally, I can ever see myself fielding one. It is far too expensive and is massively overshadowed by the old reliable Stegadon.