I find it deeply amusing that people think the changes to Spirit Guardians is some kind of OP buff.
Spirit Guardians now does damage once when the emanation enters a creature's space and when they end their turn in it. That is it. This means a cleric can run into a group of enemies and deal 3d8 damage. And if the enemies do not flee, they take 3d8 at the end of their turn. IF they do flee, no extra damage.
Do you know how it USED to work? People would use Telekinetic or Eldritch blast with Grasp of Hadar. They would stop right before the enemy, then hit them with those abilities, pulling them into the spirit guardians for 3d8 damage, then at the start of the creature's turn, they would take another 3d8 damage. Then on the next turn or as a reaction the caster would find a way to push them out or flee, then pull them back in, and they would repeat the process. They could also get allies to do the same, pulling the enemy out, and pushing them in.
If anything, the exploit is WEAKER than it used to be, because now moving the enemy around in and out of the spell effect doesn't do anything. You have to move the spell effect, and depending on the exact wording, it might ONLY work if you move the emenation on your turn, dropping us from potentially 12d8 damage before the enemy can react to 3d8.
I'm more worried about Spiked Growth cheesegrater strategies than Spirit Guardians. WRT Spirit Guardians I was originally responding to someone who said that you should avoid exploits by just not playing with people who used exploits, when said exploit is "walking around a bit so that more people got hit by Spirit Guardians." If a game's mechanics can be exploited by walking around a bit then there's something wrong with those mechanics.
Comparing 5e and 5.5e spirit guardians. Unless I'm missing something in 5.5e mechanics the way to squeeze more damage out of them is to:
1. Move around a lot so that more critters get included in the AoE.
2. Flee critters who are next to you (or push them away) so you can repeat #1 next turn.
Similarly the 5e way to squeeze more damage out of SG was to:
1. Position yourself so that at least one (ideally a bunch) of critters are just outside the range of SG.
2. Knock said critter into the range of SG.
3. Then the caster has to flee or push the critters away (not just from AoO range but out of SG range).
4. Then people have to knock the critters back in.
With the 5e way that's a lot of pushing and pulling, a WHOLE LOT of pushing and pulling and some very exact positioning that is going to be hard to do with more than one critter.
Just like I doubt that I'll ever have to deal with weapon juggling as a 5.5e DM, I never had to deal with those kind of tactics as a 5e DM despite running games for years and how much pushing and pulling and precise positioning has to be done makes it seem like not a big problem for me if it did happen.
Meanwhile the much simpler way to squeeze more damage out of the 5.5e SG rules make it seem like the sort of thing I'd be more likely to see at an actual table in which the PCs are fighting a whole bunch of mooks and the cleric just lawn mows through them. Not really that big of a deal in most fights, but annoying some of the time.
Don't see anything wrong with the solution of nerfing SG a bit and making the damage only proc on the start of a critter's turn.