Twilight Sparkle: Going to shift here and Magic Missile the clone near me.
SFX: (ZAP!)
DM: You point-blank blast the changeling out of its Twilight form. If that's all you're doing this turn, then–
Twilight Sparkle: No, not quite done yet. I think I'm going to use my action point this turn. Looks like Applejack could use a little help over there in that dogpile.
Applejack: Yeah, it's gettin' a little intense over here.
SFX: (ZAP!)
Twilight Sparkle: Oh, you don't mind if I AoE the whole spot, do you? I'll use Enlarge Spell to reduce the damage rolls.
Applejack: It's fine, Ah can tank it. Though Ah'm startin' to kinda wish you'd taken some friendly fire feats.
It's hard to create a situation where you can revel in the players hitting each other when they're sometimes perfectly willing to deal and soak up damage to and from each other anyway, under normal circumstances, sometimes without prompting.
That's one issue I have with DnD, particularly 4th ed - the "padded sumo wrestling" combat meme. In my lite gaming, I sometimes eschew hit points altogether, and just cause "appropriate" damage to players and NPCs. The kids I play with are too new and excited to notice.
Also Synaptic Static. Which I used, not realizing the reason the monk was OK with being hit with a Fireball wasn't that he could tank it, but that he had the Dex/feat combo to nullify the damage. And Synaptic Static is an INT save. WHOOPS.
It super-annoyed one GM when our party had a really fun combo where my rogue and the party monk grapple the boss and then the wizard fireballs us all. Evasion abuse FTW!
One of my favourite remarks about fireball over at the Giant in the Playground forums was someone writing something to the effect of, "I told my party that if they didn't want to get a fireball, they shouldn't stand somewhere that deserved a fireball. Never had a problem after that."
Current tank I am playing is a Spheres of Might Sentinel (Dimensional Defender). I tank well (DR and high hitpoints from other things), and I use that to teleport replace people so friendly fire is not as much an issue. Just got to 108 hp at 5th level. ...I also am a Spheres Summoner Synthesist, so pretty much have double hp and am encased in a body armor elemental (which gives my DR...and Physical stats...and limbs...).
We were playing Starfinder, and I was playing a medic. One of the weapons I had was a Syringer, a weapon that fires syringes of whatever delightful concoction you can come up with. We were facing off against Akata, some pretty nasty hombres that bite you and infect you with their larval young.
We knew that Akata were vulnerable to salt water, so my medic starts loading his syringes with the saline from an IV bag. Great idea, right?
I roll to hit, and get a 1. My shot hits the soldier right in the back of the neck.