Is there a particular placement for heros to make stronger attack/defence?
Oh, you wanted advice…
The center position takes the most hits, so it’s normal to place a tanky hero there, one with good health/defense who will absorb a lot of hits, ideally hurting the foe along the way. See Top 5 Tank Heroes In Game
Another mechanics issue to consider is that, if several heroes have their specials charged, they fire form left to right. So imagine you just got a glorious tile run and all your heroes are now ready to fire; how do you want to sequence them?
Final point: many heroes’ special hit three targets, often with a center hit plus splash damage. Also, tile drops can hit adjacent heroes. So the usual rule is to separate colors physically to avoid sjount da,
Mage from a strong color, for example, putting a yellow hero center flanked by purple can be very tricky to take down.
@Kerridoc covered defense positioning very well. I’ll also note a few interactions with heroes that buff themselves and nearby heroes which apply to both attack and defense teams.
1.) Nearby attack buffs - Lancelot, Ares. Position these two next to your heavy hitters with offensive specials.
2.) Nearby defense buffs - Magni, Khagan. Position these two next to your heroes with low defense to help them survive. These will often be your heavy hitters again, but could also include healers with high attack stats.
3.) Perfect Riposte - Cyprian, Boril, Elena. Position these three next to heroes with the highest health / defense ratio to maximize the damage returned.
4.) Nearby color specific defense buffs - Kashhrek, Domitia, Guinevere. These are trickier but try and position them so that they are covering allies who best use that buff. e.g. if you run Kashhrek center you shouldn’t put a blue hero next to him since they already resist fire.
It almost goes without saying, but heroes that buff nearby should not be placed in the corner, which would waste ⅓ of their special.
A further related thought: Riposte is almost always placed dead center, thus giving splash/hit-3 heroes no room to cast without taking damage.