Culdcept SAGA

GibGirl is correct about the use of only earth (green) creatures. What I have found is that the easiest way to get this achievement is to load your deck of about 20-25 creatures. and use the rest to give yourself "ITEMS" to help in attcking lands or defending lands. There are a few creatures that are very useful, Wall of earth allows you to take over a land and for all practical perposes keep it if you level up the space or have another way to boost its defence. The card silence can be invaluable as it makes it so that your opponent cannot use creatures for two turns. Use this late in the game just before he is about to go through an area where you have Big tolls and your opponent is forced to pay.
Werebear and any creature with support works well also(as there are many of them.) I personally choose to play the colliseum III level (victory condition 8000) and then just played as many critters as i could. leveled the green spaces up first if possible with a secondary option of converting other lands to earth when at a safe area of the board.

You may be asking "hey, I thought that you have to obtain 10000 for the achievement to pop?" This is true but it is not hard to level up a few lower lands on what will be your last trip around the board to put yourself over 10,000.

I will post my decklist on here that i used later.

For this achievement, you do not have to have a deck that consists 100% of earth creatures. Spells and items are allowed. The deck must contain at least one earth element creature, and no creatures from any other element, no multi-color creatures, and no neutral creatures.