Can anyone hint me on how to make one? I've been fusing like hell, but still nothing. I was so happy when I thought I had it, but unfortunately I made it with hama... someone please help?

Well, I kind of do these without checking guides and stuff, and I never remember which Arcanas I should mix, or how the levels affect the outcome, so I do it "the long way". I don't remember which two Personas I used for Matador... Sorry that I can't be more useful...

First, if you need Mahama, you usually have to start with a Persona that has it already (sometimes a certain Persona might get it after leveling up). Since Matador doesn't have it or learn it naturally, I think, you absolutely must use a Persona that has it already. If you look in the manual, there is a big table that tells you which two Arcanas you should mix (for Normal fusion). Since Matador is Death, according to the manual you could fuse Hierophant + Empress or Priestess + Fool, etc (however, the levels are important, too). So, your goal when fusing should be to have a Persona of one of those types with Mahama.

Looking at my Compendium, I have the Power Persona of the Justice arcana (and Mithra of Temperance, too) with Mahama as a natural skill . So, I start fusing him. However, when selecting the fusion, make sure Mahama is going to be inherited in the resultant Persona. Really important (in bold!): If you don't see it in the list, cancel your selections and re-select them, until you see it. (There are some spells / abilities that are impossible on some Personas, so if after many tries you don't see it that may be the reason). With this new Persona with Mahama, I go and check the fusions to see I have the correct Arcanas / levels (triple fusion can be useful here, too). If not, I try to do the same process but create another Persona of a different Arcana with Mahama. And so on and so forth. After a while, you will have many Personas with Mahama and you will probably find the combination you need. Not the best approach, but it works. (Many times you need one or more "intermediate" Personas with the skill you want, before you can fuse the one you actually want).

For higher level Fusions, your goal should be to get at least one of the required Personas with that skill. You can use the process above to do this (but can be tricky, since there are more possibilities).

(If you want to be more efficient, you can check the Fission calculator someone that posts at NeoGAF made.... It tells you which two Personas you should mix when giving it the one you want. Or the Fusion calculator, too. I don't like to use this kind of stuff, however...)

I had forgot about the table on the manual, I'll use that.

I also don't use any form of guides, that's why I asked for more general hints. If I try mixing these I'll probably be able to get it more easily.

Ok, let me tell you the answer to the problem. Get Anzu to level 20 and it learns Mahama. And combine with Berith to get Matador with Mahama.