I'm close to getting a 4th level of Assassin Rogue with a character I'm playing and I'm torn between picking up the Alert feat or improving an Ability Score (i.e. +2 Dexterity) so:
Which is best, an Ability Score Improvement or the Alert feat for my Rogue?
Obviously the main ability scores are important, but the potential is there for me to ignore ability score increases entirely and focus on feats exclusively.
The Alert feat, in my opinion, gives some great advantages for almost any class:
- You gain a +5 bonus to initiative
- You can't be surprised while you are conscious
- Other creatures don't gain advantage on attack rolls against you as a result of being hidden from you.
The initiative bonus is pretty self explanatory – a high Dex character gets a decent shot at going before almost everyone or it could mitigate unlucky rolls.
Practically never being surprised is also a huge plus – you can react to, and potentially even negate, ambushes and sneak attacks against the party.
Finally, preventing advantage on attack rolls against you from hidden characters removes a huge portion of an attacking Rogue's potential to sneak attack your character as well as reducing the chance of actually being hit by all hidden attacks. At worst, if someone gets advantage against you, you'll probably have seen them coming first.
Combining this Feat with the Rogue's Assassin lvl. 3 feature (which my character has) seems even better:
Assassinate
Starting at 3rd level, you are at your deadliest when you get the drop on your enemies. You have advantage on attack rolls against any creature that hasn't taken a turn in the combat yet. In addition, any hit you score against a creature that is surprised is a critical hit.
The bonus to initiative gives you an even higher chance of consistently getting a sneak attack in combat and an auto-crit on the first sneak attack of an ambush can cause huge damage, potentially ending the combat before it even begins.
All of these advantages make me think the feat is superior to the benefits of +2 Dexterity (or another Ability Score Increase).
Personally I don't think the extra +1 AC from +2 Dex (for example) is as good as the benefits of this feat, especially with 5e's bounded accuracy, but I could be persuaded otherwise…
(Edit: My question isn't aimed at discussing which feats are the best. But even so, this feat seems to be one of the best in the PHB and a fairly solid choice for almost any class…)
Best Answer
Here's what you're trading for the alertness feat if you don't take the abil score upgrade and instead take the feat:
The question then, ultimately, becomes, is +5 init (net +4), no surprise and no advantage on attacks against from hidden opponents worth it.
The latter two features are very dependent on your campaign and DM. Surprise should be a fairly frequent occurrence on both sides of combat, but that still depends on how willing your DM is to allow it or stage his monsters to have them obtain it (and kind of how cautious your group tends to be). Monsters attacking from hidden is another one that really depends on your DM, you group and how well you guys are at nosing out monsters from the shadows.
So ignoring those two items since they are DM and campaign dependent (and thus can't be weighted objectively), the question then becomes, is +1 to Dex more or less beneficial over 4 levels than +5 to init.
For pretty much any character other than the Assassin Rogue, I'd probably argue that they should take the stat upgrade early, the feat at L8 and then the last stat upgrade. However +5 init has amazing synergy with the Assassin Rogue and you're going to get a ton of mileage out of it.
If you're already at 20 Dex (if you managed to start at 20, or 18 and are at L8), then there really isn't any stat upgrade that is worth taking over this feat (though there may be better feats). Rogues are skill monkeys, yes, but +5% in a single ability set of skills is not worth the +25% to initiative and other features o this feat. The only one that would be worth considering at all is Con for the extra HP, but it's really not that many and you're better of boosting your damage significantly.
Take the feat at L4 (or even better, play a human and take it at L1).