With his wife focused on depowering Cooler, and Goku, Raditz, and Chuu Lee still doing their best to hold King Cold off, Acer stares down the tyrant facing Trunks. They're about equal at this point, sure, but if Cooler catches hold of what's keeping him from overpowering Trunks...

No.

"RAIO-TEN!" he roars, bringing up his sword. There's a chance this will all fail. A chance he's going to die horribly. A chance he's going to take if it means keeping Chi-chi from becoming a target.

Trunks and Cooler exchange blows, the young Saiyan trying to get a good strike in with his sword, but the tyrant keeps anticipating every slash. A strike to his jaw via Trunks' elbow sends Cooler back, but right as Trunks attempts to swing down Cooler's tail swats at his hands, followed by a kick to the head. But Trunks keeps fighting, well aware of how dangerous this task is. As he's kicked away Trunks releases a barrage of Ki blasts at Cooler, repeatedly hitting his face. He swipes at the Saiyan with a wave of energy, forcing him back again, then notices the Tuffle bolting at him. He points down, Ki building up at the tip of his finger.

Acer keeps flying, foresight telling him of the incoming barrage of beams. Each one a death sentence if it hits. He dodges as best he can, Cooler's frustration mounting after every missed shot. It gives Trunks the opportunity to head back again and try to attack, managing to get Cooler in the back of the neck with a surprise kick, but as he tries to slash down Cooler's hand strikes him in the head. Acer finally manages to reach them, Cooler catching his hand right before he can thrust his sword into Cooler's side. He squeezes hard, causing Acer to drop his blade.

"Hah! You move like a sick puppy, boy." he mocks... only to get a Ki blast to the side of his face from another source. More distracted than hurt, the tyrant turns to the source and declares, with relentless hatred in his voice, "YOU!"

"I said you'd pay for every life lost because of you, Cooler, and I meant it!" Lazuli yells. Trunks hesitates as he sees her, mind conflicted. The blonde woman fires again at the tyrant, pelting him with Ki blasts he easily manages to deflect. A Destructo Disk follows the bursts of Ki, only for Cooler to fire a pair of beams from his eyes at it, destroying it with one and striking Lazuli through the leg with the other.

"You know, I could tell you every last detail of how your terrorist friends died. One by one. How long each of them suffered. How clear the message that traitors would be punished was." He chuckles with malice in his voice. "Which ones cracked under the pressure."

Lazuli holds her leg in pain, but keeps her focus on Cooler. "B-bastard..."

"But I have a better idea; I'll force you to experience it all yourself! If you're lucky, I can tell you how far each one got before they couldn't take it. You've already done better than two of them!" he roars out a laugh, grip tightening on Acer's arm.

The blonde swordsman sees a brief premonition. If he wants to make this count...

https://www.youtube.com/watch?v=9vUtM9iySqg

Cooler's darkened aura flares around him as he swings Acer around to try and strike the young woman while using him as an improvised melee weapon... but with his free hand open, Acer telekinetically grabs his falling sword and swings it into Cooler's back. It doesn't strike too deep, but it does what it needs to. The aura begins to dissipate, his borrowed power no longer merely being held back by Chi-chi's technique, but vanishing for a moment, and dropping further.

Cooler shouts out in pain, a manic expression on his face. "THAT'S IT, THIS PLANET VANISHES, WITH ALL OF YOU ON IT!" He lets go of Acer and brings two fingers above his head, creating a tremendous sphere of Ki.

"TRUNKS, FOCUS EVERYTHING YOU HAVE INTO THIS NEXT ATTACK! WE ONLY HAVE ONE MORE CHANCE!" Acer yells, both hands back on his sword. The enchantments of the blade give it a mystical shine. "Guys, this is gonna be risky, but we have to try..."

Trunks powers up, his own borrowed strength slowly starting to dissipate, but he does as asked. Cooler turns to him, ready to throw the planet-busting attack right at the Super Saiyan.

Then it's sliced in two.

The Masamune cleaves the sphere of destruction, Acer moving as fast as he can out of the way before it ignites, catching up to Trunks and charging with him. The two swordsmen, flying at full speed, slash at Cooler, leaving a clear X-shaped mark on his torso... and all the way through. Cooler's attack finally ignites, leaving a blinding flash behind them both as his body is eradicated.

King Cold looks back at them in disbelief. "That... that's impossible... YOU... YOU CAN'T BE CAPABLE OF THAT!"

Heart racing, breath heavy from the effort, Acer looks to Trunks and smiles. "N-not bad, Super Saiyan..."

Trunks smiles a genuine, earnest, almost fanboyish smile back at him. "You're something else yourself... uh..."

"Acer."

Lazuli looks past them, eyes watering as she lets out a nervous, but happy laugh. "H-he's finally gone... we got him, Dresan."

Trunks hears the woman's voice and gives an uncomfortable glance at Lazuli. He breathes out an "Uh..." before a titanic surge in power comes to King Cold. "YOU WILL ALL SUFFER FOR DISGRACING MY SON!" the cyborg tyrant howls into the air, the ground around him trembling.