So, in short, yes. [mwcard=MWSTX2FFQ01]Adramelech's Torment[/mwcard] requires Line of Sight because it specifically says "target creature".
All being MtG players, we had exactly this debate (knowing that in MtG and similar games, there's a world of difference between 'targeting' a creature and say 'choosing' or 'selecting' a creature). However 'Target isn't a keyword ability in the rulebook (even v4).
What I didn't find in the game was the Targeting section on p15 of the full Rules and Codex document, which effectively makes it so (or at least a defined game term) - it's clear there.
Thanks!