Nightfall strikes are basically just heroic strikes except you not only could put on different modifiers to make it harder or easier for you and your team but you can also higher your handicap with your challenge card.

Nightfalls keep score on every kill you and your team get the higher the score the higher your chance to get a nightfall specific loot will be and raising your handicap and putting on challenging modifiers raise your score multiplier. each one of these loot drops have their own lore tabs.
Exodus crash
this nightfall gifts you a rather sleek looking sparrow named impact velocity

Lore:
“Captain, this conveyance’s top speed is a fraction of the Exodus Black’s when it crashed into Nessus!” “Try not to find out for yourself.” —Failsafe
FAILSAFE NAVIGATIONAL AI RECOVERY PROTOCOL EXBLK .QAR UNRECOVERABLE (!CFIT !) EXBLK.CVDR ONLINE 32% INTEGRITY DEST : KOI-571.05 DIST : 151pc ~~492ly ~~161pc~~552ly~~141pc ETA: ##^^^$%%~~~~~~~ samBLA: —rbit of 7066 Nessus is different from what the Cos— EXCEPTION CAUGHT IN NAVIGATIONAL COMPUTATION ALGORITHM. ATTEMPTING MITIGATION. MITIGATION FAILED. QUADRATIC IRRATIONALITY INTRODUCED. INCOMMENSURABLE. RETRYING. INCOMMENSURABLE. masJAC: —djust course two degrees. It’s a long w— COMMAND SUGGESTION NOT SUFFICIENT. OVERRIDING TO 8.5 DEGREES. OVERRIDING TO 8.7 DEGREES. echo My apologies, Captain Jacobson! My formulas to calculate our trajectory have encountered 26 new mathematical constants. I’m attempting to compensate! UNAUTH PROGRAM INJECTION DETECTED. CUADRIDIMENSIONAL STRUCTURE COMPROMISED. ATTEMPTING MITIGATION. kaoZUY: —st lost the starboar— echo I’m sorry, but I’m unable to keep pace with what is happening to my computational capabilities! The Exodus Black is now in an unrecoverable descent. Please make whatever preparations are appropriate! HULL LOSS IMMINENT. IMPACT IMMINENT. echo I’m sor-
Inverted Spire
if you are lucky enough to get this one dropped (these loot drops are pretty rare) you’ll get the trichromatica a ghost shell that musta had a good day cuz he’s just glowing!

Lore:
“Void, Solar, then Arc. Hmm. We’re not naive enough to think the order is a coincidence. But we’ve got bigger things to worry about.” —Zavala
I’m not sure why my journaling subroutine has come back online! It’s quite troubling. (All the things to freak out over and my diary is top of the list?) The Red Legion’s drilling has impacted my processing in some way! That shouldn’t be possible. My concern is escalating! (Calm down, me. There’s always something I can do.) But rewriting my own pathways isn’t permitted by my original programming! (Neither is whining.) That was uncalled for! I’m refocusing on identifying the source of this change. (No, I’m going to make those red losers regret coming to our little rock.) No, I’m analyzing the oscillating nature of the Modular Mind’s shield to find weaknesses that can be applied to anti-Cabal weaponry. Why am I doing that? (Because I’m doing it, not me.) …This is all very worrisome! (Yeah, I should get an external diagnostic run. By no one. Because they’re all dead.)
Pyramidian
at the end of this nightfall strike you have the chance of getting the silicon neuroma sniper rifle

Lore:
“My future is concurrently irreversible and unknowable. Before it overtakes me, I desire a more abrupt end to those responsible.” —Asher Mir
A staggering Vex detonates, and the Exo Hunter is torn in two. One half sinks beneath the lake’s opaque surface. Asher’s eyes go wide and he freezes. Whatever they’d stumbled into down here was multiplicatively more lethal. He reloads his fusion rifle and looks around wildly. The other Hunter—she’s the only other one left alive, no, stay calm—throws a smoke bomb and disappears. Asher barely has time to react before the Hunter reappears on high ground and draws a bow of Void energy, almost in slow motion. Crack! Crack! Crack! Ten Vex fall. Asher watches them disintegrate, looks back up to the Hunter—but the yell of gratitude catches in his throat as four Vex shimmer into existence behind her. Asher can’t watch this time. He frantically searches for a way out… and a tentacle grabs his Ghost. A millisecond of pain in his shoulder and everything goes white.
Savathun’s Song
at the end of this rather dark strike you have a chance of getting the duty bond assault rifle.

Lore:
“Due respect, Commander? I was there when the Hive found us on Earth. I was there when we stopped them on Titan. And I’ll be there when we wipe them out.” —Sloane
Taeko-3 was smirking again. Sloane liked a lot of things about her. The smirk wasn’t one of them. “Sure. A weird Hive ritual. Nothing we haven’t seen before, right?” Sloane gripped the railing. “Everything under those waves is something we haven’t seen before.” The Hunter behind Taeko rolled his eyes. The railing crunched under Sloane’s hand. “You worry too much, boss! We’ve dropped a thousand Hive with our Sparrows. When the three of us”—the Hunter flourished a blade, and the other Warlock cocked a shotgun; did they practice this?—”are working together, we’re unstoppable.” Sloane walked forward and put her hands on Taeko’s shoulders. The smirk disappeared. The Hunter’s blade dropped, but he caught it out of the air. “Taeko. They’re not always going to have your back. What are you going to do when you’re the last one standing?” The smirk came back. “Easy. Embrace the Praxic Fire.”
The Arms Dealer
once you manage to make it past those flame turrets of his and kill him then you got a chance of getting this unique sparrow as a reward

Lore:
“[whistle] With a few more revs, Zahn woulda turned this thing into the fastest bomb you never saw. Good thing for all of us he never got the chance.” —Amanda Holliday
It would only take one shot. That ridiculous ceremonial armor had 10 weaknesses that Bracus Zahn could spot without even looking that closely. One good shot, and everyone else would abandon this foolish crusade on this miserable planet— “This is all of them? The most advanced weapons you have?” Zahn tried not to lose his temper. “Would I have made the trip all the way to this ‘throne room’ without them?” It was a lie, of course, but this puffed-up “Dominus” didn’t need to know about the experimental vehicles Zahn had been working on since— “Were I you, Zahn, I would think hard before giving so flippant an answer.” This was the “Consul” who had deposed Zahn’s best customer. Zahn didn’t turn around as he said, “If I were you, roach, I would think hard before wasting the time of the only real weapons supplier you’ve got.” Growls from all over the room, but Zahn smiled. They needed him. And they knew it.