A lot of the upgraded cards are very unfair to beginning players. I suggest limiting the number of upgraded cards that can be in a deck. I highly suggest making it so the max number of a certain upgraded card that can be in a deck be 2. There should be a higher limit for pillars. Probably 5.

Also, since I like thinking up cards, here is an idea
Briar Garden 6 earth
permanent
summon 5 briars that deal 3 damage to an attacker.
3 life: Put 2 briars on this.

The briars are one use, like bone shields from bone wall, and they only effect one creature each. Also, they don't effect creatures with momentum. Upgraded version gets more briars or they deal 4 damage.