Hey people

I am busy designing a sniper for AL play. The basic idea is

• Rogue 4 (assassin)/Battlemaster x
• Race: Half Elf for the extra stat boost and flavor.
• Playstyle is a mix of stealth sniping and battlefield control from BM maneuvers (Pushing, distracting, and precision strike are priorities)

The question is, am I better off using XTGE as my + 1 for Elven Accuracy (Reroll one advantage die) or Tashas, for the Steady Aim optional class feature? 

Steady Aim

3rd level

3rd-level rogue feature
As a bonus action, you give yourself advantage on your next attack roll on the current turn. You can use this bonus action only if you haven’t moved during this turn, and after you use the bonus action, your speed is 0 until the end of the current turn.

Going with Tasha's also frees up some other possibilities:

• No Elvish Accuracy frees up an ASI, which I would probably fill with piercer (+1 to dex, bonus damage on crits). 
• Without Prioritizing Elvish Accuracy, I could start out as Vhuman and get Piercer or maybe Xbow Mastery from the outset. 
  
  Another question - does it make sense to start with fighter or assassin first? This seems like a choice of balanced options to me. The best argument for going fighter is to get to 2 attacks ASAP. But I have never before played a rogue, so going 1-4 Assassin first might be more fun, if less effective. 

Steady Aim is pretty useful for battles in open plains or small rooms or whatever else prevents you from stealthing to get advantage. But I think smart play as a Rogue and taking advantage of your environment can accomplish more or less the same thing... just take expertise in stealth and you can get yourself advantage easily in most combat situations. Elvish Accuracy is a beast, especially if you're good at giving yourself advantage. If you stick mostly to Battlemaster, you'll get more ASI opportunities than going pure Rogue, so that opens you up to more feats. I know from a player having this combination in a game I DM... but Elvish Accuracy paired with Sharpshooter can lead to some insane damage output.

Here's my recommendation... start Rogue so you can get Expertise in Stealth and your cunning action as soon as possible. That seems to be the bread and butter of a sniper build. Hold off on taking on the Assassin subclass just yet. At level 1-5 you don't really need the boost in surprise damage the subclass gives you, because at that level very few creatures can survive a surprise attack anyway, regardless of the guaranteed crit damage. At that point I'd recommend going Fighter for 5 levels to get extra attack and Elvish Accuracy, then dip back into Rogue to get Assassinate. After that just go full-on Battlemaster and try to grab Sharpshooter at some point... although I'd try to, at minimum, get your DEX up to an 18 before taking that extra Feat. 

Honestly, you don't really need the Assassin features. As fun as it is to get a guaranteed crit, it's actually kind of a pain to pull off a surprise attack in AL, since it's hard to sneak ahead on your own to pull off, and all it takes is one Paladin in plate armor to ruin a stealth attempt to sneak up on some guards. What you really need for this specific build from Rogue is just your Cunning Action at level 2 for the disengage and hide options to pull off sniper moves.

I have considered a rogue-based sniper build with the sharpshooter feat and piercer feat. Definitely using tasha's. Take a 1-level dip in fighter for the archery fighting style bonus and longbow proficiency. Variant human so the pile of feats can be used earlier in the level progression, starting at level 8+ use elf (probably wood elf).

Quote from TransmorpherDDS >>

Steady Aim is pretty useful for battles in open plains or small rooms or whatever else prevents you from stealthing to get advantage. But I think smart play as a Rogue and taking advantage of your environment can accomplish more or less the same thing... just take expertise in stealth and you can get yourself advantage easily in most combat situations. Elvish Accuracy is a beast, especially if you're good at giving yourself advantage. If you stick mostly to Battlemaster, you'll get more ASI opportunities than going pure Rogue, so that opens you up to more feats. I know from a player having this combination in a game I DM... but Elvish Accuracy paired with Sharpshooter can lead to some insane damage output.

Here's my recommendation... start Rogue so you can get Expertise in Stealth and your cunning action as soon as possible. That seems to be the bread and butter of a sniper build. Hold off on taking on the Assassin subclass just yet. At level 1-5 you don't really need the boost in surprise damage the subclass gives you, because at that level very few creatures can survive a surprise attack anyway, regardless of the guaranteed crit damage. At that point I'd recommend going Fighter for 5 levels to get extra attack and Elvish Accuracy, then dip back into Rogue to get Assassinate. After that just go full-on Battlemaster and try to grab Sharpshooter at some point... although I'd try to, at minimum, get your DEX up to an 18 before taking that extra Feat. 

Honestly, you don't really need the Assassin features. As fun as it is to get a guaranteed crit, it's actually kind of a pain to pull off a surprise attack in AL, since it's hard to sneak ahead on your own to pull off, and all it takes is one Paladin in plate armor to ruin a stealth attempt to sneak up on some guards. What you really need for this specific build from Rogue is just your Cunning Action at level 2 for the disengage and hide options to pull off sniper moves.

 Starting tonight more-or-less following this advice. It's historic, so I am not even sure I can use Tasha's.

you could always go drow and shoot with impunity in the dark...kinda sucks in direct sunlight though but imo, the night-time bonus is better than the daytime penalty