I watched the tutorials twice, read through all the help, I've even beaten the game a couple of times (on normal difficulty) but I still don't understand how locking glyphs works.
Sometimes I can lock a glyph, and sometimes I can't. Sometimes I can lock a glyph for other people, most times I can't, and even when I do, it doesn't seem to do anything.
I know there is a spell to lock a glyph -- does that mean you can lock 2 glyphs.. assuming the mysterious magical formula for a "regular" lock works?
Normally you can only lock a glyph if you can't complete any of the tasks at the adventure. This is known as 'focusing'. If there is another character at the same adventure with you (and you fail to resolve a task) you can lock a 2nd glyph on that character (this is known as 'assisting'). If there are more characters at the same adventure, you can use all of them to assist, as well, so it is possible to lock up to 4 glyphs on a single failed role if all characters are there (however, I don't think I've ever done this- it almost never makes sense to lock that many). Focusing and assisting can only be done once per turn- once a character has been used for either function, they won't be able to focus again until their next turn, or assist again until the next character's turn (provided they're at the same location as the active character). Focusing and assisting does not require the use of any items.
You can use most spells to lock a glyph, even on a successful role when you are able to complete a task. Obviously, you only want to lock something if it can be used on a remaining task. The tabletop version allows other characters to use dice that have been locked with a spell cast by a different character on their turns (if not used by the caster), but Omens does not- only the character who casts the spell can use the locked dice, and if you don't use it on that turn, the spell is wasted.
There is one character, Jim Culver (only available if you purchased the Ithaqua campaign), who allows you to focus even when you succeed at resolving a task. He can also be used to assist in the same way. I have found him very useful on several occasions.
Hope this helps.