The one and only important thing is that Army has to be a creature and you need to be its controller
Urborg, Tomb of Yawgmoth + Yavimaya, Cradle of Growth Urborg, Tomb of Yawgmoth and Yavimaya, Cradle of Growth occupy a similar space of making all lands duals of a sort
If an effect has given Infesting Radroach -4/-0 so that it's a -2/2 creature, doubling its power gives it -2/-0, and it becomes a -4/2 creature
The older the card the more lenient I am when it comes to condition because some cards are just really hard to find
Plus, whenever another Creature dies, you get to put a +1/+1 counter on Ob Nixilis
Sword of Forge and Frontier Land and card draw The Swords of series in Magic: The Gathering run a gamut of usefulness, but all of them cost three mana, grant protection from two colours, add +2/+2 and provide some kind of benefit if you can hit a player with a creature equipped with them