To memorize something abstract like a kanji, you we must to connect it with something, like some nominal meaning (which doesn't have to be entirely accurate or complete).
(If we do not connect the form with something else, then what does it mean to memorize it and to recall it? If something has no association, yet we are able to recall it, all we can do is point at it and say "I am sure I have seen that form before": basically, the form is associated with a "Yes" or "No": yes, I have seen it; no, I don't think I have.
And it ends there.)
A mnemonic device just serves to help retain and recall an association. The details of the mnemonic do not matter, as long as it makes sense to you and helps you remember. You can (and should) make up your own mnemonics.
Mnemonic devices can build on your existing knowledge. For instance, in regard to this 烙, I already know 各 which means "each", "every". I do not need a mnemonic for that character any more. (I do not remember whether I ever had one). So I might build a mnemonic based on treating this with two parts, rather than three: perhaps combining the concept of fire, with each and every.
Here is what might work for me: 烙印 (rakuin) means brand: a symbol that is burned on, like on cattle. How about: "Each and every one of my cattle is branded".
You don't have to associate 烙 with the nominal meaning of "burn" given in some dictionaries; you can use something else, like "branding". The accuracy isn't critical, because this meaning-word is only an access key to the other information you will later hang onto the character, like the words that it is involved in.
By the way, I could also reinforce my memory by noting that this character has a similarity with 客 (kyaku: guest, visitor, customer) and that sounds like yaku (burn). The customer lost his hat, and got sunburned. "The customer complained that he lost his hat, and got sunburned". (客 -> lose hat -> 各 -> burn -> 烙; kyaku, kaku, yaku).