First example is the new Dragon Egg from Magic 2014. Dragons are large creatures, so it makes sense their eggs would also be large. Sure, some see dragons starting out at lizard size and simply growing to some exponential size of its birth size, but that's always bugged me. I much prefer the big dragon egg. Let us see what the art description called for:
"We see a reptile's leathery egg laying in a nest of gold coins, gems, bits of broken armor and weapons, and charred bones. The egg, which is at least 8 feet long, is ready to hatch..."
Dragon Egg | Art by Jack Wang
Looking at the art you can see the weaponry around the egg, providing an idea that this egg is taller than a sword, leading us towards the eight-foot-height note in the art description.
Our next example of scale is from Magic 2014's Millstone artwork. Done by Yeong-Hao Han, here's what the art description called for:
"Maybe it is an enormous millstone that sits flat on its side on top of a huge, sculpted head... it has slowly, magically turned for years so that the stone head is worn down, the millstone now sits at its eye level."
Millstone | Art by Yeong-Hao Han
Looking at the above art you easily can tell that it's a large millstone, but only when you look closely are you able to realize that there are tiny people standing atop the central axle of the Millstone.