I thought there were tips on here about 105, but I must've been mistaken. I'm stuck on another timed level right now, so no way am I gonna play 105 again (LOL!) But I took a picture...the only strategy that comes to mind is basic digging & doom jewel tips.
I'd start the level with a good move or two, like the circled red match on this one:
or the red doom jewel match on this one:
Better yet, hold out for a couple good moves. If you don't have them, restart the level. No use making moves at the top that don't help you when time is so crucial. It shouldn't take an energy if you don't touch anything. And it gives you a little "head start."
Also, just make as many blasters, bombs, diamonds, etc. as you can, and combine them for more powerful digging. Set off your bombs & blasters close to the dirt if you can--focus your matches at dirt level, too. (But keep an eye out for doom jewels & special jewel-making opportunities.) If it's a choice between strategizing or just moving--just move! Keep the sides "dug down" so your screen scrolls, and preferably set off your blaster/bomb combo's when you've got more dirt on-screen. I don't remember if there's enough time on this one to use a diamond+blaster, which can eat away at the clock. Might wanna use diamond +bomb instead. And again, watch out for those doom jewels!
When you reach the bottom, if you have time left on the clock, clear any remaining doom jewels & stop making matches.* I kept going, wanting to get a better score. Well, what I hadn't thought of was that the doom jewels would keep falling! I was luckily able to clear them & go on to pass. But I would've been crushed if a doom jewel would've got me after spending so many days trying to pass that level (and I have a feeling you would be too, lol!)
*Aileeniweeni recently reminded me of this--read her post in the Unicorn Summit thread for more info.
Best of luck! 105 is definitely on of the tough ones!