With the new engineer update, some old tactics seem to no longer work against certain sentries. Specifically I'm talking about a level one with a shield. The only ways we found to bring them down was to send a spy in to sap then have an ubered demo lay a stickie nest around it and blow it all away. Soldiers and heavies straight on ubered seemed useless unless they got on top of the sentry or we had a scout or something distract it. Anyone else find anything that works?
If the Wrangler is your main problem, I would recommend the same tactic as against the heavy/medic combo: shoot the little guy to take away the big guy's advantage.
Focus on shooting the engineer first, as opposed to earlier when only killing his sentry mattered. This is the main difference.
Also, move fast. remember that with the Wrangler, the sentry's accuracy depends only on the engineer, so on a human. If you make a rocket/sticky jump, for example, he will have difficulties to follow. Same for a scout.
Since you're playing a heavy mostly, your best bet vs a wrangler engineer is tanking. Team up with a medic out of range but in sight and start building up ubercharge. This will prompt the engineer to start attacking in your general direction, because you're a direct threat to what the sentry is defending.
While you do that and sustain some damage, you should let your teammates finish the job. The bane of a wrangling engineer is the sniper. Usually the main reason for your continued wrangling is you need to cover an area that is too large for the standard sentry range to safely cover. Most maps are indeed arranged this way. A wrangler allows the engineer to overcome this and gain moderate long range capabilities.
However, that means exposing yourself to snipers. The engie can deliver a fast stream of low DPS damage in the sniper's general direction (the sentry's aim assist helps here) while the sniper can zoom in and go for the headshot, or the charged bodyshot. One shot one kill. Once the engie is gone, the same sniper can easily destroy the exposed, shieldless sentry. As you can see, one good sniper can get rid of an unwary engineer quite effectively.
Since the sniper usually takes cover in dark corners as far as possible from the sentry, this usually spells doom for an engie; he just has to rely on his teammates to take them out, or he has to notice them, in which case the engineer must defend his sentry, rather than the point.
This covers long range engineers; for smaller areas, there's really no need for wranglers except in a few situations:
Other stuff that can be effective against wranglers is stealthy backburner pyros. If you're wrangling you're usually doing tunnel vision to the area you're trying to cleanse. A pyro can just run in and burn everything down in seconds.
So, we've covered the heavy, the medic, the sniper, the scout, the demoman, the pyro, the soldier, what's missing? Um, ah, yeah, the engineer, but there's really not much to say about that. Just place a nearby teleport 3 and eventually everything will sort itself out.
So that about wraps it up! As you can see a wrangler engineer doesn't really have an easier life than before. He's still awfully vulnerable to all other players and will fall at the first mistake. So long as you're playing a real cla—
Respawn in: 12 seconds
Bah. So, yes. The spy. The wrangler is useful for the extremely paranoid engineer, who can just fire his sentry blindly all over the place, perhaps get lucky and hit a cloaked spy and get an achievement for it. However, the engineer must remember that a sentry, while wrangler, fires at twice the rate. That means it consumes ammo, and thus metal, twice as fast. Basically you can't be firing forever.
This means that you can use the wrangler to spycheck, but only if the spy's visible in some way. In this case a non-dead ringer spy doesn't really hold a chance. A dead ringer spy has to move away from you, due to his loud decloak sound, so at least you can reliably fend hi—
Respawn in: 25 seconds
...unless he has the spy set, of course, in which case he can decloak a little bit closer to you. The loud firing of your sentry doesn't help you. As usual, the only counter the engie has for this is his teammates. Nothing new here—
Respawn in: wait next round
Dang nad dabbit, however that goes. I hope this helped though. It sure isn't going to help me…