Trey explains his unique magic Doodle Suit (hidden meaning: Let’s Paint the Roses) as the ability to overwrite characteristics, saying that “it only lasts a little while” and “it’s kinda like covering up the real thing.”
Later we learn that Trey may have been intentionally downplaying his own ability: when he overwrites an overblotting Riddle’s magic, turning murderous rose trees into playing cards and dissolving the collars made from Riddle’s own unique magic, he surprises everyone including Riddle and Cater.
Trey explains, “I used it to make ‘Riddle’s magic’ into ‘my magic'” and Cater responds, “That’s some kinda loophole!”
Trey downplays his own accomplishment, saying that overwriting Riddle’s magic is not something he can normally do and he doesn’t think it would work again.
Trey reiterates this when Leona tries to get him to overwrite Riddle’s collar in the world of Riddle’s dream, saying that it is not something he can just do on demand. He makes the attempt and fails, getting collared as a result.
In Book 7.5 Ace says that, for his unique magic to work, his target needs to have fully formulated their spell, and Trey responds, “That sounds like a limitation you could overcome with the right training. Get good enough to add any missing structural components yourself when you make the switch.”
Deuce is surprised, but then realizes that Trey’s magic is not dissimilar, asking, “That means you instantly rewrite or rearrange a spell structure, right?,” but Trey responds, “I can’t overwrite just anything. Every spell has its limits.”
Trey also uses his unique magic during Vargas Camp to turn stones thrown at the students into rubber balls, and he tells a story of a time he overwrote the taste of an upperclassman’s cake in his first year, making it spicy as an act of revenge.
Trey also uses his unique magic during Book 7 in order to save Ortho, turning roses along a pathway into metal so that an army of darkness-Caters is forced to pursue him one at a time: “Careful, those thin leaves and petals can cut as cleanly as a sharpened kitchen knife.”
Trey explains that his unique magic isn’t suited for battle, unlike Riddle’s and Cater’s, so he intends to fight the darkness “the slow and steady way,” instead.
Trey also uses his unique magic during the Nightmare Before Christmas event to make a soup more palatable. Trey quietly reflects, “..but I only changed the flavor, not any of the actual ingredients. Ah, well. Look at the way they’re smiling. Why spoil the moment?”
Twisted Wonderland Reference Note 