I used str/int on my 35 rhino (praktica). Just enough str for the gear you use. The int allows mana regen from alchemist which is nice but more importantly it gives a bit more heal (which is already a bit low compared to a mages heal) and it adds skill damage to tempest, your highest damaging skill. On the other hand though with str/dex you will get more base damage but also with dex your skill damage from charge and redemption increase. In the end I've done both ways and liked int more than dex mostly because of the mana regen and heal. Either one will give enough skill damage to do your nuke.