"Look after Ace, Kid. He needs you more than ever."
It's Sparx's death scene, in case you're wondering. Also a bit of a woobie moment for Mark because he looked so damned upset about it (thus supporting a fact that had previously been doubted: Tom Wansey can actually freaking act.)
Lady Illusion offers to take away the Human Emotions that Ace has been struggling with the entire season after Taking the Bullet for him in the final episode, calling it "her last gift to him". He tells her not to. He wants to keep them. As much as they have screwed him up and over in the last half a dozen episodes or so, they are the real gift.