3-7 SUN
3-7 Sun is the 7th stage of Cosmos Ch.3 — Even Stars Burn Out. Previous stage: 3-6 Mercury. Next stage: 3-8 Uranus.
The Face's Alien/Floating variant — 44,444 HP, 1,333 AP area attack at 366 range with 100% Freeze. Boss of Sun across all 3 chapters plus Sirius/Skelling Ch.3. Freeze-Immune frontline (Li'l Eraser, Riceball with Talent) + Anti-Alien/Anti-Floating Ubers.
2.5k 
65k Corporal Weyland and Ribbo carry Barriers (up to 65,000 HP) — your hits are absorbed until it's broken.
Ribbo's 65,000 Barrier needs a guaranteed 100% Barrier Breaker — chance-based units stall and waste your damage window.
FENCER CAT A Guaranteed 100% Barrier Breaker at long range — the reliable accessible breaker. 
MIZLI S 100% chance to break Alien Barriers. Also fits “Counter Alien.” 
LUMINA S 100% Barrier Breaker opens Star Alien Barriers for the team. Also fits “Counter Alien.” 
TEKACHI A 100% chance to break Barriers. Also fits “Counter Alien.” 
BORA S 100% Barrier Breaker reliably cracks Star Alien Barriers. Also fits “Counter Alien.” 
GRAVI S 100% chance to break Barriers. Also fits “Counter Alien.” 
I.M. Phace is 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. Also fits “Break the Barrier.” 
WHEEL CAT A Deals Massive Damage to Alien enemies — a huge area nuke against Alien crowds and bosses. Also fits “Clear the crowd.” 
MITER SAW CAT A Resistant to Alien and deals Massive Damage to Alien. Also fits “Break the Barrier.” 
CATMAN S Deals Massive Damage to Alien in every form. Also fits “Counter Floating.” I.M. Phace is Floating. Anti-Floating units take less damage and deal more.
ARCHER CAT A Deals Massive Damage to Floating enemies. Also fits “Out-range I.M. Phace.” 
BODHISATTVA CAT A Slows and (True) Weakens Floating enemies. Also fits “Clear the crowd.” CATMAN S Massive Damage vs Floating (Normal). Also fits “Counter Alien.” 
HIGH LORD BABEL S Equally tough against Floating enemies, with Colossus Slayer. 
BISHOP CAT A Its Slow only lands on Floating enemies, making it a targeted answer to Floating pushers. I.M. Phace reaches 366 range. Units that out-range it can chip safely without taking hits.
LIZARD CAT B Range 400 — fires from beyond its 366. 
RED RIDING MINA A Range 435 — fires from beyond its 366. ARCHER CAT A Range 390 — fires from beyond its 366. Also fits “Counter Floating.” 
NERD CAT A Range 1200 — fires from beyond its 366. Also fits “Clear the crowd.” CATMAN S Range 440 — fires from beyond its 366. Also fits “Counter Alien.” 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.” 
DELINQUENT CAT A Area Multi-Hit clears grouped enemies. Also fits “Counter Floating.” CATMAN S Long-range Area damage clears groups. Also fits “Counter Alien.” 
ACTRESS CAT B Hits multiple enemies at once for budget crowd damage. Ribbo's 65k Barrier + 100% Warp at 400~550 range. Snipe with waves (Major Leaguer Cat).
Endgame Sun. Ribbo as 65,000-HP-Barrier boss with 100% Warp at 400~550 range. Community fix: guaranteed Barrier Breakers (talented Crazed Bahamut or Ganglion) to delete the barrier, then Warp Immune units (Manic Mohawk, A. Bahamut, Bombercat) for the rest of the fight. Major Leaguer Cat or Catornado for wave attacks behind the front line. Common failure: ignoring Weyland's range while focused on Ribbo. Both will outrange your DPS simultaneously if you don't bring backliners — Ganglion is the consensus Uber pick here for the dual-LD coverage.
The castle you destroy to clear the stage.