Formation!!

I'm new as a tyrant of an ogre tribe.

 I realise we're bigger and have bigger base. Is there any advantage to play a unit with 3 or 4 models per rank?

From now i use to play with somes square units of 9 bull including the full command.

Is it a better strategy? Should i have a unit of 12 to have 3 rank of 4?

if it's almost the same, i'll stay with the square.

So, in that case, if i join a caracter in the unit witch model of the command should i take to the second rank.

I use 3x3 to be able to move around the field more easily. Once I'm in combat, I reform out to 4x2, sometimes wider depending on what I'm fighting. I'm not going to win from static CR, so I go as wide as I can to get as many hits as possible.

You only ever get 1 CR per rank, and that's 3 models or 9 attacks minimum. So if you can go wide, you're going to get 6 more attacks per width you go. If you can average more than 1 wound per 6 attacks against what you're fighting, you should always form out wider when you can. Against WS3 T3 you should be getting 2 wounds (4+, 3+) from Bulls with 6 attacks, so keep that in mind.

So yeah, for moving the field I go 3x3 because it's a nice, compact shape that doesn't make wheeling impossible. Once I get into combat and get the impact hits (another reason to retain ranks 'til then) I'll go wide for extra attacks.

Oh and if a character joins a unit that already has full command in the front rank, the CHARACTER goes to the second rank. Command takes preference over characters. You can use Make Way to go up to the fighting rank in combat, however.

When I run a tyrant (which I have better luck with then a slaughtermater, I have no luck with magic) I like to run them 4 wide. You get more impact hits, stomps and normal old attacks.  with a full command your wizards and bsb wtill still be able to go into the 2nd rank. If the unit just has a butcher the I'll only run them 3 wide with full command.

Reasons to go wide:

1) More impact hits. Only ogres in the front rank get impact hits.
2) more stomps. Only ogres in the front rank get stomps.
3) More close combat attacks. Front row gets full complement of attacks. Second row only gets 3. Unless in horde formation, third row and further get none.

Reasons to go narrow:
1) More rows equals more combat resolution. +1 per row of 3 up to 3.
2) Steadfast. If you have more rows than opponent, you are steadfast.
3) Impact hits are +1 str per rank behind the ogre. Against things like chaos knights, I'd rather have 3 str 6 impact hits, than 4 str 5 impact hits.
4) Easier to maneuver/position.
5) You can load your characters that are harder to kill in the front, thus protecting your easier to kill ogres in the ranks. This can minimize wounds caused.

sweet, thanks mate.

If i've got a rank of three ogres and i add a heroe in the front rank wich model of my command should i take to the second rank???

sweet, thanks mate.

If i've got a rank of three ogres and i add a heroe in the front rank wich model of my command should i take to the second rank???

None, the Hero goes into the second rank. When it is time for combat he can use the Make Way rule to move to the front rank if he wishes(which normally he would want to do). Please read the Command  and Character rule sections of the rule book again starting on page 92. of the BRB and ending on Pg. 107. That section should help you figure it all out.

When it comes time to make way, don't send the Bellower to the rear. Musicions only function in the front rank while Banners function anywhere.

So the order of sending to the rear for me is Banner, Champion, Bellower.

Normally I don't have Champions so there is always 1 slot open in the front rank.