I will go over the individual points you've mentioned:
card draw: This deck really is lacking card draw. Dimir has the best pool of cards for drawing them. Cards like
Stinging study really fit your style of Voltron/Control deck. Maybe have a look at
Sire of Stagnation.
Also, with drawing more cards, you will draw more ramp and gas for the late game.
ramp: Some say 50 sources of mana is right. I wouldn't go as far, but in my opinion your numbers are too low. And PLEASE don't
forget the
Oblivion Sower, which is the most absurd card for the deck.
mutate: Sadly mutate is a trap. tried it myself often enough
![Délire :D](https://deckstats.net/forum/Smileys/default/cheesy.gif)
focus: I don't really like to mention cards to remove or add, because this way you could just go to edhrec and streamline your deck. But I have to mention some cards as an example.
1. Remove the pile of "
Flicker" cards in your list. You have like 5 creatures with ETBs. The value these cards are adding is marginal.
2. Your pile of "
Exile Cards" is to big with some weird choices in it.
Denying Wind will either be a dead card for most of the game or an underwhelming effect when casting. Most of the other cards are dead draws in the late game or won't do anything early.
I would go with the 1-mana-artifacts and some incidental graveyard hate like
Author of Shadows or
Szat's Will with some big upsides attached to them.
Most often it will be sufficient to remove just one graveyard to have your commander deal lethal damage.
3. There are just 2 reliable removal spells in your deck. And none of them mass removal. Your deck probably will develop much slower than your opponents. Without removal you won't catch up. I always go with at least 2-3 mass and 4-5 spot removal cards.
4. Your "Counter/Control"-package is kind of fitting the theme. But unfortunately not very useful in commander. Try to swap in hard counters for the "pay x" counters.
5. General focus of the deck. Umbris himself is more of a voltron commander. I would suggest to go this route combining it with control. Remove those expensive cards that don't do enough and replace them with cheap ways to mill like
Maddening Cacophony for example. I would also go with cheaper Horrors which can attack immediately after casting Umbris. There are even some fun ones like
Mindslicer,
Phyrexian Obliterator and
Overcharged Amalgam ![Clin d'oeil ;)](https://deckstats.net/forum/Smileys/default/wink.gif)