Thank you for this (and the previous guides). Helped me get up to Insane dungeons quick when the artifacts came out, and just today I unlocked the Blitz one by three starring 1-3.
Most stages I just followed your guide, but while your guide reliably got me past 1-3 I could not three star it. To do that I had to go in from the bottom right corner, and build up a few Celebrates before I hit the enemy heroes. But as you always say - adapt to the specific situation - just putting it out there for others that might have trouble 3-starring it for the artifact.