I've been able to clear this map consistently with about a 99% success rate using this build.
The listed stats are simply the stats my heroes currently have equipped, not necessarily the minimum requirements.
I use two Summoners with Huntress and Apprentice Guardians, along with a Tower Boost Monk. Once all upgrades are completed, I switch to whichever hero I want the weapon reward for.
In practice, I never leave the North Core to check on the other crystals. Occasionally, if a Gas Trap takes too long to trigger, the other cores may take damage or, in rare cases, even be destroyed if the trap fails to activate entirely.
Other than that, the build is very straightforward and can be comfortably AFK'd once everything is upgraded, as long as your Tower Boost Monk keeps boosting.