The burning sun strat is a bit easier to time if you use higher level cards like the phoenix and maybe Time Reader, who can raise one unit's level by 1 and give them +10 AT permanently.
When we were testing we used Refess as the "Default" deck. If we were worried about a combo (like fairy dance / exploding spores) or (Dalos/anything) or (Fire Dragon/Earth Dragon) or single card being too strong, then we'd play it against a standard, no endless morning, no cards higher then rarity 3, mostly set 2 Refess deck. The idea was if Refess couldn't win in three tries (the three tries was for the Refess player to figure out a strategy) something was wrong. Whenever that happened, we tweaked something.
I think that playing Refess with a self-buff deck (all the cards that give AT bonuses), probably including Lycanthrope Angel for his 1/3 turns buff, will be pretty effective in general, but if Refess wants to be really, really competitive the best way to play I've found is to super conservative with SP. Maintain an SP advantage over a short term tactics advantage. To do that, you need to keep in mind some big rules of SP.
1 - Using SP to bring out a unit is investing SP for the future, because you will get it back.
2 - Using SP to power a special ability burns away that SP forever. I think Folrart Trick Shield Knight is one of the best cards in set 2 and I only used his Skill once in 20 games.
3 - Reviving a unit burns away that SP forever.
4 - Grimoires except for Recovery Powder burn SP forever.
5 - The only way to do huge damage on command without spending SP is to use Soul Cards.
If you can survive the early game using Soul Cards to do your big damage and keeping your guys alive as long as possible, minimizing revivals (if possible, letting a card go to the cemetery and bringing it out again gives you a 1 SP advantage, if that soul card you just set off forces the enemy to revive two units, you've got a 3 SP advantage over him) while forcing your opponent to use Grimoires and revive, you'll get a big SP advantage in the mid-late game. Only use an SP burning Skill if it will force the enemy to Revive and keep your SP costs the same on both sides of the board. If everything goes okay, you should have enough SP to bring out your level 4-7 cards while he'll find he's out of good level 2 cards to throw down and he'll have to wait to bring out something bigger.
So what about returns? Well, if the enemy uses a standard return Grimoire on you, it won't give him any SP advantage, but it could weaken your field position, causing you to get hammered and be forced to Revive. That's always a danger, but hopefully your SP advantage will help you recover. If you make it to the end game, his Returns won't matter as much. Thankfully for dealing with Witch, Refess reliance on level 3 units actually turns into an advantage.
Also, this new look at SP gives me more respect for Holy Light, a card I used to think was terrible. In the end game, LP and cards have a pretty high value. Holy Light effectively gives you both. (LP because it lets you revive your sacrifice cards like Wisp and Armed Citizens you wouldn't normally revive). 5 SP is steep, but you are also saving the cost of Revival. If you revive 2 units, you're cost is 3 SP to (effectively) get 2 cards from the Cemetery. If you revive 3, you're paying 2 to get 3. But the real value of Holy Light is this... you're cards have lots of HP, there a bit of work to take down, but the enemy has lots of ways to do this, Grimoires, Soul Cards, "glass cannons", etc. You can't really stop him from taking them down. However, if you engineer it so that they all fall at once (and remember, he's trying to get that to happen, too, so it's not as hard as it sounds) by choosing when to rest, and who to heal, then having them all pop back at once with Holy Light, you've created an intimidating situation. You've got a whole bunch of high HP units on the field with full HP all at once. Since Refess cards come out slowly, by the time one high HP unit is on the field, the enemy has usually put down or severely weakened your last high HP unit. Your enemy has probably never seen 3 high HP Refess units on the field all with full HP at once! All of a sudden, taking them all down seems like a very lengthy prospect and it's the end game, where hopefully you have enough SP to do stuff and he doesn't.
"Scissors are overpowered. Rock is fine." -Paper