I've already written about no damage and critical kind of attacks, but there are some more things that should be avoided. I will name one more: weakness of some attacks. I am going to give some I know and I guess you know them too but I'll make a.... revision :
a sea attack gives a weak attack to
the dragons with sea
element as first element;
a fire attack gives a weak attack to
the dragons with fire,
terra element as first
element;
a terra attack gives a weak attack
to dragons with terra
element as first element;
a nature attack gives a weak attack
to dragons with
nature, sea
element as first element;
an electric attack gives a weak
attack to dragons with
electric, dark
element as first
element;
a metal attack gives a weak attack
to dragons withmetal,
fire element as first
element;
a dark attack gives a weak attack
to dragons with dark,
ice element as first
element ;
a light attack gives a weak attack
to dragons with light
element as first element;
a war attack gives a weak attack to
dragons with war
element as first element;
a pure attack
to pure;
a legendary attack
to
legendary.
This is what I know for now.