Yes, I know about horde traps, I need to specify more >.>. I would say that the corruptor is either. For weaker players, your only choice tends to be taking out the portals to prevent enemies from swarming you. In the end, it's down to your heroes and playstyle really.
While going through a level normally, you shouldn't be getting surrounded like that, unless that is your plan in the first place, my Viper for example.
Even when in a horde, you would need almost constant healing for it to make much of a difference. It also means the hero doing healing isn't attacking very much. While you can start the healing and then cancel it and the buff will remain for all 4 seconds, for some reason, it seems to take at least a second to be able to cancel reconstruct. In the end, you're using all of that power, just to give 4 seconds of -25% damage and a single tick of healing if you're doing this.
One thing of note though, is that it's one of the small few of offense items which have +health.






