Nice and Simple... Just some spell ideas

The ideas:
I have 2 ideas for spells, as follow:
1. The Reverse Shield Spell
Alright, the name of the spell is enough to surprise anyone. But the reverse shield spell is much better than the name implies.
After you drop the spell, a white dome pops up from the aura of the spell. My original idea was that any of the projectiles fired from the defenses which hit the aura of the shield would bounce back at the defense it was fired on. However, my newer idea is that any projectiles that hit the aura will bounce back randomly, sometimes, the bounce further and sometimes they hit a building, and sometimes they miss. They can even deflect projectiles on your troops! However, if used correctly, the short time of the shield can be destructive. Mortar shells are heavy and don't bounce very far, but will almost always hit something do to the splash damage. Certain defenses can be confusing, for example, the X-Bow, Inferno Tower, Wizard Towers and Air defenses, including traps. All traps function normally, shield or not. the X-Bow could be overpowered, so 1 in 5 projectiles bounce back, the rest are absorbed by the shield. The inferno tower's rays reflect off at a diagonal direction, thus harming nothing. This is the same for the wizard tower. For air defenses, air troops can stay inside the aura, and 1 in 2 missiles will bounce off. The air defense missiles twirl back unpredictably. Which version do you like more, the one that fires the projectiles back at the defense, or the version where the projectiles bounce back randomly? Go ahead and tell me what you think.
2. The Mirror Spell
This sounds a little more self-explanatory. The mirror spell multiples troops that come into the wall of the spell. Wait, the WALL of the spell? Yes, the mirror spell places down a strip that multiplies units that enter the wall. The wall spans 5 tiles. Every 3 upgrades the wall is extended by 0.5 tiles. The spell isn't overpowered because:
1. There's a chance they'll be multiplied. With each level, the chance is increased.
2. Troops that multiply Take much less damage.
Tell me what you think about these ideas, and if you like these ideas, please rate this post 5 stars!
--hyrul