acceleration of city sieges in late game?

[Technetium]

I'm trying to perfect my deck before going against the wizards. Right now I have:
4 Mountain
4 Urza's Tower
4 Urza's Mines
4 Urza's Power Plant
4 Mox Ruby
4 Black Lotus
3 Sol Ring
4 Mana Vault
4 Disintegrate
4 Fireball
2 Earthquake
2 Rock Hydra
4 Manaflare
4 Lightning Bolt
2 Detonate
2 Candelabra of Tawnos
4 Juggernaut
1 Bronze Tablet

Been wandering beach areas looking for Mind Stealers, Elementalists, or Conjurers (all of which can walk on beach and can give the "duplicate card of your choice" reward). Just need that one last Sol Ring for the deck.

It's gotten to the point where I jump to a town under siege, and I have only time to get a short distance from that town before the next town becomes under siege. Every single attack on a city seems to diminish the time to the next attack. I'm not sure if this is an effect of the number of battles, time spent playing the game, or the fact that I've already defeated the white and green wizards. This is pretty annoying. I am not sure I'll be able to get that last Sol Ring. I've had some plans for other decks to build in other games which are pretty much going to be impossible to build with the game doing this (for example, one idea has 4 each of Time Walk, Time Twister, Ancestral Recall, Sol Ring, Wheel of Fortune, Fork, Mox Ruby and Sapphire, Copy Artifact, and Black Lotus) . Is there any way around this problem?

[jiansonz]

Yes, it does accerelerate over time spent (I think), and it does seem to get worse when one or more wizards are defeated. I usually complete building my deck before taking on the five castles in one big crusade.

(btw, Sorcerers and Elementalists can also duplicate cards for you)

Using the world magic Quickening (eats green amulets) gives you more time to move around. Leap of Fate can also help but requires luck or several blue ammies.

You may have to accept a less-than-perfect deck for the final assault.

[CirothUngol]

Is there any way around this problem?

Well... if you don't mind cheatin', there's always the Shandalar DeckInjector. ^_^
That'll alleviate your need for one more Sol Ring.