So another great debate: Legion Commander, Shadow Blade, Blink Dagger, or neither?
Shadow Blade:
+200 bonus damage on invis break
+More damage on the item itself
+More attack speed
+Easy to sneak up on supports with assuming no detection
-Detection can ruin your day
-75 mana cost
-Can be hard to time going invis and walking all the way to your target before it expires
-Expensive, more than blink
-Long cooldown
Blink Dagger:
+Instant jump to your target, no worries about detection
+0 mana cost
+Shorter cooldown than SB, with some distance, can be used as an escape assuming you don't get damaged for long enough.
+Cheaper than SB
-gives you nothing other than the blink, no stats, damage, AS, Nada
-Counterable by things like Radiance, or long range spells.
Neither:
+Allows you to get any other item
-No real way to initiate on someone unless a teammate can help (Force Staff, Earth Spirit, Tiny, etc.)
Honestly it is quite a toss up between Blink and SB. Against stuff like BH or Slardar, Blink is probably the right choice, but against something like a Spectre or Nature's Prophet, SB might be better.
http://dotabuff.com/matches/518506102
I had this match last night. I jungled, our Dark Seer didn't do so well in the offline and neither did Invoker mid. I was doing well, picking up lots of Duel wins and had over 150 damage. They still took us in team fights and split pushed to win. I only lost one Duel the whole game.
At the end their NP decided to talk shit and called me an idiot for going Shadow Blade on LC. Now he did have Necro III, but the invis isn't the only be benefit of SB. So was he right that Shadow Blade was a bad choice? I don't think so. Despite snowballing, their Morphling had freefarm and was quite scary. On top of that we had no choice but to go 50 minutes against a NP and Morphling, due to the state of everyone else on my team. Ember was quite fed. Our Sniper's farm was okay, but not set to go against that lineup at 50 minutes. Even though I snowballed a bit, I couldn't do everything.