Creature taming and summoning is about to get adjusted in Shroud of the Avatar come Release 33 later this month.
A quick forum thread identified a few changes that are in the works, including a minimum level to summon a creature and a greater focus requirement for higher-level creatures. The patch will also impact how powerful a creature is depending on the level of the tamer.
“Your taming skills will affect the power/level of your creature effectively leveling that creature as your skills increase. Note that this works both ways so that if someone with a lower level summons a higher level creature that creature will be weaker.”