Combining Skills

Way back in an old Beta (october I believe) it was able to combine multiple skills into a single skill slot. The penalties were additional mana usage, reset times, and casting times, but sometimes it was very lethal to combine spells. I remember using a slow spell with a rain spell made it difficult for mobs to move, very useful in a single cast.

Is that still possible? If so, I haven't found it. Thought someone might now if it is still there.

Thanks,
-GWFX