Need some advice on what to do next...

So, i try to focus on the basic set, spending my seals mostly on that. Here is the card´s list i miss so far

Creatures:

Tithe Collector
Elite Squire
Eleonor
Imperial Guard
Celestial
Chaos Imp
Doom Bringer
Banshee
Fate Weaver
Panther Warrior
Raging Smasher
Pao Deathseeker

Spells:

Cleansing Light
Celestial Armour
Resurrection
Stone Skin
Curse of the Netherworld
Shadow Image
Spell Twister

Fortunes:

Cassandras Imperial Devotion
Serias Legion
Altar of Asha

Events:

Week of the Dead

23 cards left to complete the Basic Set. Also i lack the following heroes:

Jezziel
Sandalphon
Nergal
Ariana
Acamas
Shaar
Crag Hack

So, the question is...what should i do next with my seals?....stick with the Basic set or change to some of the new voids packs?

Actually i spent my gold on Heroic Packs, and my seals on The Box.

Thanks a lot.