Does a Monk have any reason to take the Mobile feat?

Question

I am currently playing the Curse of Strahd adventure and we just leveled to 8. I was thinking about taking the Blade Mastery feat (from Unearthed Arcana: Feats) or the Healer feat (PHB, p. 167). A fellow player suggested I take the Mobile feat (PHB, p. 168) for my monk.

Is there any reason to choose the Mobile feat over another possible feat (such as Blade Mastery, Savage Attacker, Durable, Healer) for a monk since they already get increased movement?

My stats are:

• Str 10
• Dex 19
• Con 16
• Int 12
• Wis 18
• Cha 10

I am a half-elf of the high elf variant with the fire bolt cantrip. I have no other feats currently.

Answer 1

There are multiple benefits

Mobile feat does not only increase your movement speed. It also negates difficult terrain when you Dash and allows for the avoidance of opportunity attacks.

When you make a melee attack against a creature, you don't provoke opportunity attacks from that creature for the rest of the turn, whether you hit or not.

This is a very powerful feature for a monk especially since they can get many attacks to hit all of the enemies in melee using Flurry of Blows.

And, 10 extra movement speed doesn't hurt. There is almost never a case where you have too much movement speed as repositioning in combat (especially if you are avoiding hazards or threat areas of enemies) can take a lot of movement.

Answer 2

As David mentions in his answer, possibly the greatest bonus from Mobile is actually the bullet

When you make a melee attack against a creature, you don't provoke opportunity attacks from that creature for the rest of the turn, whether you hit or not.

However, you seem focused on the fight against Strahd, and from my experience, Opportunity Attacks from Strahd aren't exactly what you should be worried the most here. From your stats, you have 19 dex and no other odd score, and also you are a half-elf. Monks get a lot from bonus Dex - higher chance to hit, higher damage, higher AC, higher everything. This highly indicates to me that a feat with half-ASI, i.e. +1 Dex, would improve your character by a lot more than taking either a Full-ASI (+1 Dex +1 another thing) or a feat without any ASI.

I don't intend to include much math here since this is not exactly an optimization question, but Elven Accuracy from Xanathar's Guide to Everything, if you have some way to consistently get advantage, brings a decent advantage over +2 ASI (check this question for example What is better early game, dex increase to 18 or elven accuracy for fighter-rogue?). In your case, you don't actually have to trade the +2 ASI because you are already at an odd stat, so you actually get both the bonus.

As another option, if your party chooses to face Strahd only at 12th level, which is possible IIRC, you might be interested in getting +1 Dex, +1 Wisdom now, and at level 12 getting Resilient (Wisdom), giving you proficiency in Wisdom saving throws, which are helpful against his charms and some spells (such as Polymorph), and the missing +1 Wisdom, putting you at full 20 Wisdom, increasing your AC again and some damages.

Answer 3

The reason for the Monk to take the Mobile feat is not the extra movement, but rather to not provoke opportunity attacks from any creature that you have attacked, hit or not. This is extremely useful as you can move about, attack a large number of targets, and then escape without even been attacked!