Help with Luna?

Not every strength hero has to tank up, and Eye of Skadi is an obvious choice over Heart of Tarrasque unless you save for buyback, in which case you just don't get either. (he did mention any carry hero)

Also Eye of Skadi, works especially well because most of the time str carries are melee heroes with very low mana pool until late game, and Eye solves both problems with slow and int. It gives only 15 less str (so 15 less dmg) for 2 armor, tons of mana and slow.

@Xyrus:
It's not about the fact , that midas is punishable.
The item itself doesn't really provide any useful stats for Luna. It is usually bought to boost up your XPM not GPM on Luna. It doesn't delay your BKB for too much, but you hit your level 11/16 way earlier, which can be crucial for certain Midgame push/teamfight strategies.
In terms of pure Farmspeed HotD+Yasha is pretty much as good as a midas would be.