Green flame Blade can't be twinned
For a spell to be twinnable it needs to only target one creature. As clarified in the PHB errata:
To be eligible, a spell must be incapable of targeting more than one creature at the spell's current level.
Green flame blade is able to target two creatures; the one you attack and one next two it. (See also developer ...
RAW: Yes, Crown of Madness can be Twinned
The text for Twinned Spell:
When you cast a spell that targets only one creature and doesn’t have a range of self, you can spend a number of sorcery points equal to the spell’s level to target a second creature in range with the same spell (1 sorcery point if the spell is a cantrip).
And the ...
As written, Sculpt Spell has specific boundaries that constrain the spell area.
As a DM I'd rule no simply on wording, but there's also a similar issue with Sculpt Spell I found here, whereby a sculpted spell is still capped by the spell's range (their example is using a sculpted Burning Hands to make a 40 ft cone. The range if burning hands is 15 ft, and ...
Dispel magic ends the effect on only one target
1. This is a confusing area. RAW would appear to suggest that dispel magic should end the effect on both targets:
The rules for twinned spells state:
When you cast a spell that targets only one creature and doesn’t have a range of self, you can spend a number of sorcery points equal to the spell’s level to ...
Only one target will be affected by Dispel Magic in this case
Dispel Magic states:
Choose any creature, object, or magical effect within range. Any spell
of 3rd Level or lower on the target ends. For each spell of 4th level or higher
on the target, make an ability check using your Spellcasting Ability .
The DC equals 10 + the spell's level. On a ...
There is nothing preventing you from applying Repeat Spell, Empower Spell, or Maximize Spell feats to Time Stop.
... but you would not get the desired effect
First and easiest, Maximize Spell doesn't maximize additional portion of the spell gained through Empower Spell. Your lower cap would be six rounds - five from maximized portion of a spell,...