Unfortunately, and unlike the achievement system in World of Warcraft, there does not seem to be a way to track achievements on the main GUI. You can, of course, continue to track it via the achievement UI, but that's not generally something you want to have open in the middle of a boss fight.
The thing about this particular achievement, though, is that it'll pop up as soon as you achieve it. So until it shows up and you get the toast, know that you've still got skeletal minions to let get killed.
The achievement is called "Attention to Detail" which made me believe there must be a difference in their looks... but only if you're paying attention.
I found some comments over at WoWHead that indicate the boss's mirror images are slightly different. I will copy in some of these comments.
Option 1: Look closely!
You can look at them and pay close attention:
CORRECT ILLUSION
Black headband,
Black hair that goes over her shoulder,
Black chestpiece
Black shoulders
BAD VARIATIONS INCLUDE
White shoulders
White hair
Short hair
Sapphire-White headband
Ruby-White headband
White Chestpiece
Option 2: Macro/chatbox solution
You can also make a nice macro (or type a script into chat) that will show you the model of the original boss alongside a model of your current target, which should help with quickly identifying the right one:
First, this one:
/run frm = CreateFrame("PlayerModel");frm:SetPoint("BOTTOMRIGHT",nil,"BOTTOMRIGHT",0,100);frm:SetHeight(600);frm:SetWidth(300);frm:RegisterEvent("PLAYER_TARGET_CHANGED");frm:SetScript("OnEvent",function(self,event,...) frm:SetUnit("target") end);
It will show a huge model of your current target at the right of your
screen.
Then, target the boss and use that one:
/run frm2 = CreateFrame("PlayerModel");frm2:SetPoint("BOTTOMRIGHT",frm,"BOTTOMLEFT",0,0);frm2:SetHeight(600);frm2:SetWidth(300);frm2:SetUnit("target")
It will display the original boss next to your current target.
After that, the achievement should be easy
And to deactivate the model box:
/run frm:UnregisterEvent("PLAYER_TARGET_CHANGED");frm:Hide();frm2:Hide()
Best Answer
50%
The Console achievement Hallowed Be Thy Name requires your world to be at least 50% Hallow. The Dryad NPC can tell you how much of the world is Corrupt/Crimson or Hallow.
If you're looking for more area to Hallow, remember to spread Hallow to the underground areas as well. The Cavern layer, which is primarily composed of stone, is where you'll do most of your underground work. Hallowed Seeds can be used to spread the Hallow on the surface, but you'll want to use the Clentaminator with the Blue Solution to spread the Hallow to stone blocks underground in a timely manner.
Source: http://terraria.gamepedia.com/Achievements#Xbox_360