My first monster will be dragons, I counted the attacks per minute in real tibia while they weren't moving thus had not the extra 1.4 seconds attack delay. I counted the attacks of dragons while a knight attacked them resulting in the following values:
dragon
12 1 wave 1 ball 1 heal
16 2 ball 1 heal
22 3 ball
7 1 ball
16 1 ball 1 heal
21 1 wave 3 heal
12 1 wave
10 2 wave
15 2 ball
16
13 1 w 1 b
16 3 b 1 w 1 h
13 3 b 1 w
189 seconds 8 waves 17 balls 7 heals
= every 23.6 seconds a firewave every 11.12 seconds a fireball and every 27 seconds a heal
The first column are the seconds and the other values are the spells the dragon used.
Without the 1.4 seconds extra delay while moving this means for your xml files:
<attacks>
<attack name="melee" interval="2000" max="-120"/>
<attack name="fire" interval="2000" chance="8" length="8" spread="3" min="-100" max="-170">
<attribute key="areaEffect" value="firearea"/>
</attack>
<attack name="fire" interval="2000" chance="17" range="7" radius="4" target="1" min="-60" max="-140">
<attribute key="shootEffect" value="fire"/>
<attribute key="areaEffect" value="firearea"/>
</attack>
</attacks>
<defenses armor="24" defense="24">
<defense name="healing" interval="2000" chance="8" min="40" max="70">
<attribute key="areaEffect" value="blueshimmer"/>
</defense>
</defenses>
If you want the dragon to have the extra delay for spells while moving then set the intervals to 3400 for the wave and the fireball. The armor value comes from a tibia statistics page that doesn't exist anymore but I found the values to be really close to the real values.
