Newly Semi-Limited

Mystical Space Typhoon
Chaos Sorcerer
Snipe Hunter
Ojama Trio
Magic Cylinder

Mystical Space Typhoon - Back in the day, we used to run 3 MST, 3 Trap hole, (me)2 Dust Tornado, Torrential, MForce, Monster reborn, dark hole, raigeki, change of heart, snatch steal and delinquent duo and call it a deck. With MST going to 2, a lot of people think that setting single spells or traps is a guaranteed bad play. In a lot of instances it is. With no heavy storm, you should PROBABLY set 2 face-down on the first turn, barring specific plays. But what is the benefit of running 2 MST? Decks right now are already tight on spell/trap space. I feel like the 1 MST being an even exchange in game resources is often enough, and the second should only probably be sided. Of course, if you're running a deck that doesn't use as many advantageous cards that only your theme can use, then a second MST might work. Lets take zombies for example. Only after you've maxed out on Book of Life, and the necessary amount of each good generic s/t card, should you start doubling up on things like MST.

Chaos Sorcerer - A boss monster in our soon to be "Intro to Chaos" deck. Actually, many people will be running "chaos decks" this format, which is basically their original deck with 2 chaos sorcerers in it. It's a good card, don't get me wrong. And it can even be splashed into many decks. But I don't think running 2 is for everyone. And I'm sure many people will give up on their "chaos decks" when they realize the reason they never ran chaos in the first place.

Snipe Hunter - I didn't even know this was semi-limited. Roll a die and you have a 60% chance of destroying a card, which is pretty cool. Unfortunately, he comes at the cost of hand resources. In a deck where discarding leads to an advantage, such as fabled decks (sorry, darkworlds do not work. Don't get cheated out of a win because of this.) Won't be seeing any increase in play from me. In all honesty, the card is not as good as Raigeki Break in Fabled decks either. Your normal summon is better suited for Kushano or Raven.

Ojama Trio - With all the synchroing going on, you'd imagine this would be allowed sooner. Eating up monster zones is not fun though, and is often used in decks that have a win condition besides attacking lifepoints with strong monsters (burn decks). I've considered using 2 in an Aslla Piscu deck, but she's still a bit too inconsistent to try to use. Either way, if your opponent is using burn, then it might be time to side in the newly unlimited royal decrees.

Magic Cylinder - I used to use this in EVERY deck when the card was first released. Negate an attack and burn for very nice damage most of the time. Even with all the MST and dust tornado back then, magic cylinder was a very good card. With no D.Prison, Sakaretsu, etc. there is no comparison. Now, the card has slowed down substantially, just as much as Mirror Force. There is a reason why Ring of Destruction is banned and this isn't, Ring can be chained at any time. Magic Cylinder suffers from the fact that it is only usable at 1 time. Using 2 can take 3000-4000 damage from your opponent fairly easily, but not as consistently as you would think. I may try 2 in the Amaryllis deck, but we're still undecided.