Are the following homebrew feats balanced with the official feats?
- You gain proficiency in darts, if you do not already have proficiency.
- You have a +1 bonus on any attack rolls to throw a dart.
- You can use your darts as melee weapons.
- Your darts crit on 19-20.
- Your darts ignore half cover, get a -2 penalty for 3-quarters cover, and a -5 penalty for full cover.
Twice per short rest, you gain an extra bonus action or an extra reaction on your turn.
When you cast any spell, you can choose to do the maximum damage possible, setting all damage dice to their maximum values. However, at the end of your turn you must make a DC 20 Constitution saving throw or suffer one level of exhaustion. You must choose to maximize before you know whether the spell hits.
Once per day, you can gain a +10 bonus to a spell attack roll. You must decide to gain this bonus before you roll.
You can make the Help action as a bonus action.