1) Grant Bahamut casts with each Aetherflow (draw enough Aether to summon Demi-Bahamut, makes sense)
2) Summoning Bahamut doesnt release existing pet (no more rouse lockout). He will attack same Obey target with no funky Wyrmwave timings, lost Wyrmwave DMG recovered by Bahamut summoning every minute instead of every 2 minutes, boom.
3) Physick now has sustain effect on your pet, bam fixed.

#1 will fix heavy punishment for death or missed Fester/Painflare because Aetherflow will just come back and grant Summon Bahamut. Gone are the days that you get 1 Aetherflow stack back (nerfed dmg from stack loss).
#2 will fix the rouse lockout, make rouse and Aetherflow for Bahamut summonings super sexy. Not having to waste all your skills (virus plz) just for a Wyrmwave makes sense. Besides, more Bahamut and more Deathflare > More Wyrmwave! It will also allow summoners to use Summon II again.
#3 Sustain is back, rejoice!