All druid spells have a max caster level less than or equal to 20. This means by level 20 you will have maxed them out. Actually i am unsure about enveloping swarm and creeping doom... And fire seeds is 21. Oh well my point is still valid.

If we are in seasons herald we can get another 3 max caster levels for the season, but also get 3 caster levels. So fire storm forexample will now be max caster level 23 and caster level 23. If we are in elemental form we get another +3 max caster level and caster level to fire or cold spells.

Dragonborn is as far as i know the only enhancement that can give +2 max caster levels and only +1 caster level to elemental spells.

With master of the wilds – the epic feat – we can get +10 max caster level to the sla spells. For now lets forget about seasons herald and elemental forms as these gives both caster level and max caster level. This gets produce flame to 25, creeping cold to 28, call lightning to 25, salt ray to 20 and finally word of balance to 30. From Primal avatar we can get +5 caster levels for druid spells. This gets us to 25. but as you can see we are still under creeping cold and word of balance. In fact we need 3 for creeping cold and 5 for word of balance. If dragonborn we need 6 for creeping cold.

Also note from what i can gather the max caster level for creeping cold is 28+2 dragonborn +3 [Color] Dragon Spell Knowledge (Draconic)+ 3 Master of [Spell School] (Magister)+ 3 season + 3 water elemental = 42. But note if in magister you loose 5 caster levels on epic destiny so you need somehow to increase caster level by 9. If we are in primal avatar we loose 3 max caster levels and get 39 but gain 5 caster levels and gets us to 35 caster level.

The only way i can see how to fully use these extra max caster levels are +3 evocation caster levels from the Greater Might of the Abishai set from chronoscope and Legendary Conduit of the Soul totalling the +5 extra caster levels for word of balance. I forgot about pendant if azure sea/sky which gives +1 caster level for cold/fire spells and reflection of wave for +5 caster levels for cold spells.

If in summer season from seasons herald this would make the effective caster level of word of balance 33. This would net the base damage of word of balance to 32/2*(25/2)=200 for creatures one step away and double that for creatures two steps away from true neutral. I think it is possible to get 600 force spell power and plus 300 for metamagics. So 200*10=2000 and if we crit that’s double. And if it is two steps away and we double crit we get 4 times 2000=8000.

So let’s look at some of the epic spells:

Tsunami is scaled of character level and so does not improve with cold or evocation max caster level. The same goes for Burst of glacial wrath which just does a flat 30d6 regardless of caster level. Please note that this is based on the description from the wiki and ingame spell description but not on testing.

My point on all this is be aware of what the spell or sla scales of. Caster level or character level if it even scales at all.

Also the caster level written in the combat log is not correct. I seem to remember having a caster level of 42 on creeping cold which was not possible on that build. I am unsure if it simply ignores max caster level or just altogether is messed up even more.