Ok so I am trying to make a demonic portal deck that is good enough to use in Adventure Mode but I have no idea how to build a proper one. So could some one help me with building one?

This is what I used. Cheap and very effective.

Dimizar lv2 -Don't evolve him to 3, Attack bonus is a liability when you play Portal
Edrianne - A must have, her Recycling ability is awesome
Iron Mask - Good for thinning your deck to 19 cards since he plays Revealing The Secret at the beginning of the game.

These are core, put them then fill your deck with defensive cards:
2-3x Demon May Rise - you need only one to attach to boss, but carry 1 or 2 more for increased draw chance
3x Demonic Portal
3x Daemonium
1x Revealing the Secret - if you have Iron Mask.

For good defensife cards consider something like Double Clay, Perversion.

A version my friend used, replace Iron Mask with Amidaraxar and Revealing the Secret with The Forbidden Book. Gives you a better last-stand if things don't go your way.

some cards to recylce portals: contact, break the second chain, reciclar la magia

wanted/freeze/sentence are useful against some bosses

also some defensive cards like double clay or brawl with dimizar are fine

_________________
My (outdated) decks

create a new post if you want to communicate with me, DONT SEND PMs!!!!

CURRENT STATUS: OFFLINE / NOT MODERATING

A little late but thanks. The deck worked perfectly.