I used a 3/45 5* Gladiator Hulk when I first did it XD , I would recommend using Red Mags, a shock immune champ like Doom or Mole Man (idk if guardian is shock immune), or use a cosmic like Medusa or Aarkus and make sure to get the armor shatter. White Mags could possibly work but Red is better.
Comments
Would make it easier.
Cheers!!!