I just completed Infinito Challenge Levels 142 &143 without any issues. I switch my characters to Sirius + Cutie Claire + Elisa. I had to face 2 Elemental bassed monsters for each level. First was the Queen of Ice Tempest then it was Tetra Pod. I had issues with tanking since it was Elemental based attacks. So my Sirius took a lot of damage. However it didn't stop us from beating those infinito challenges. I plan to retire from doing anymore infinito challenges since it's getting harder with each new level. At least made it past Level 140. Which is fine for me I don't plan to reach level 144 or higher because it's not worth my time trying to get level 150 with +8 & +7 Greek Croma's LOL xD.