1-6 MERCURY
1-6 Mercury is the 6th stage of Cosmos Ch.1 — Beyond the Exosphere. Previous stage: 1-5 Venus. Next stage: 1-7 Sun.
Shibalien Elite, Hyppoh and Star Peng are Alien. Anti-Alien units take less damage and deal more.
GROSS CAT A Its True Form is Strong Against Alien, giving budget anti-Alien value. 
LI'L GROSS CAT B True Form has a 30% Knockback vs Alien. 
WHEEL CAT A Deals Massive Damage to Alien enemies — a huge area nuke against Alien crowds and bosses. Also fits “Clear the crowd.” 
SURFER CAT A Area Freeze vs Alien controls Alien groups. Also fits “Clear the crowd.” 
CATMAN S Deals Massive Damage to Alien in every form. Also fits “Clear the crowd.” 6 enemy types stack up here. Area attackers hit the whole push at once instead of one unit at a time.
VALKYRIE CAT A Hits the whole group while it freezes them. WHEEL CAT A Hits every Alien in a wide area at once, melting grouped Star Aliens. Also fits “Counter Alien.” SURFER CAT A Area damage hits grouped enemies. Also fits “Counter Alien.” CATMAN S Long-range Area damage clears groups. Also fits “Counter Alien.” 
ACTRESS CAT B Hits multiple enemies at once for budget crowd damage. Anti-Metal Titanium Fruit cluster begins. Metal Dogees and Metal Hippoes appear alongside Shibalien Elite and Star Peng. Critical Hit cats (Island Cat, Manic Eraser at high level) handle Metals; Anti-Alien handles the Pengs.
First Star Peng test in CotC under a MAX 20 restriction. Kang Roo (Traitless Multi-Hit) plus Hyppoh and Shibalien Elite create the front-line pressure; Star Peng warps your backliners. r/battlecats calls this 'the Warp Immunity midterm' — the stage where you find out whether your backline holds up to a guaranteed 500-range warp. Lineup: tight roster pick — Mohawk + Manic Mohawk + Bahamut Cat → 1-2 Warp-Immune backliners (Bora/Lumina line, Rover Cat Mk II) → Awakened Bahamut for rushes between Star Peng spawns. Common failure: assuming MAX 20 means 'bring fewer of what you'd normally bring.' It means 'pick 20 cats that handle Hyppoh AND Star Peng simultaneously.' Cut anything that does neither.
The castle you destroy to clear the stage.