Use the exceptional hedron crab to mill the crap out of opponents.
Hedron plus fetch is good, i used esper panorama's rather then expanses, because they are stored better. (the 1 mana you can still get out of it). The clone in there is mainly to copy the stongest creature of your opponent. But can also be used to get another crab, if needed.
Shifting sky works GREAT, with all the color things in the deck. Deathmark/doom blade/hideous end are much more effective(shifting sky @ green). And if your opponent gains to much to kill off, use infest/twincast or shifting sky/hibernation.
Some counterspells to harrass your enemies, and telemin performance/mind funeral to mill specific. A deck with just 1 or 2 creatures is easily destroyed by telemin performance, the same is true for lands and mind funeral.
Haunting echoes, is not a game winner, but it mainly means, your opponents only has basic lands left. Good to use before using telemin performance, because mainly, all nonland permanents have been removed (some exceptions).
Rise from the grave is very usefull, if you mill a creature you really like (like akroma, lord of extinction, or whatever) you can put it into play. And it'll pound your opponents.
Time warp, is not that usefull, but it never hurts to get another chance to draw a land card, put it into play, and mill another 3 cards, sometimes that's all you need.
Ancestral vision, is usefull if played in the first 3 turns. Lateron in the game, the 4 turns you 'll have to wait are just to damn long. but 3 cards are nice. Also if you CAN make your opponents draw them, and maybe twincast them (to kill them off).
This deck works pretty well against semi fast decks.. and slow decks in particular, because all this deck needs, are 2 crabs, 5 mana, shifting sky, and it has a very stable foundation.
Against fast creature decks. Only real defence is infest. But that also kills of your crab. And fast decks don't have stong creatures, so it's practically useless to rise one, or use telemin.
The biggest problem is with red burn, with instants/sorceries. Only 4 counterspells, and thats NO way near saving your life.
All & all, a pretty nice deck, with some stong features and some weaknesses.