The very last card to be spoiled for Mirrodin Besieged:
A nice, chaotic effect that may occasionally help you. Attached to a plain old 3/3 body. Galvanoth is not the first weird beast to come out of Mirrodin, there was of course the original Arc-Slogger. This time around we get the Galvanoth, who has a less-dependable ability but maybe a more powerful one.
It all depends, I suppose, on the instants and sorceries you keep around.
One of the nice things I like about this card is that it doesn't reveal your top card unless you decide to cast the spell. So many other similar effects start out with a reveal to all parties.
Another thing I like is that the cost of the ability is free. While Djinn of Wishes gives you a bigger, more evasive body attached to a similar ability, you have to pay an astounding 4 mana for the privilege.
So there are two possible outcomes to an upkeep with Galvanoth on the board.
1. Nothing happens, you get to see your top card and can proceed with your turn as normal.
2. You get a free spell.
I would guestimate that this ability will fire off about 25% of the time, with the rest of the draws filled up by useless land and those tricky creatures and enchantments. And when I do show an instant or sorcery it could be many things. And of course I don't have to cast any of it if I don't want to.
Are there cards I would love casting with Galvanoth?
Yes. In no particular order:
1. Disaster Radius - A classic example of a huge explosion that blows up all of my problems in one big ka-boom! The huge mana cost is averted by my Galvanoth, very simple and to the point.
2. Rite of Replication - Here things get a little trickier. Galvanoth allows me to cast the main part of this spell for free. However, I am allowed to pay "additional" costs, which in this case would be the kicker. So my copies of other creatures cost me a grand total of about 1 mana per creature. Sounds like a pretty good deal!
3. Demonic Tutor - Why would I want to offset a paltry 2 mana with Galvanoth? That's the beauty of this situation…free spells are free spells. In this case, I can work on spending my mana for the spell I find with my tutor. Every advantage gained doesn't necessarily have to blow people out of the water, its advantage all the same!
4. Fumarole - Because I was around during Ice Age, I have quite a few of these cards. No one else seems to think they are any good. But I've always been happy to pay 5 mana and 3 life to destroy both a creature and land of my choosing. Now I only have to pay the 3 life!
5. Evincar's Justice - In this case, I can still pay the "buyback" cost. The rest of the spell is free. So not only do I get to cast it off the top of my deck, but then I get to put it back into my hand!
Galvanoth seems to be expanding my mind, always a good sign for a potential deck addition. We'll have to see if I stumble across it in my many wanderings.