Selesnya Loft Gardens

Oracle Text

If an effect would create one or more tokens, it creates twice that many of those tokens instead.

If an effect would put one or more counters on a permanent, it puts twice that many of those counters on that permanent instead.

Whenever you roll H, until end of turn, whenever you tap a land for mana, add one mana of any type that land produced.

Card Rulings

6/1/2012 Effects that place a counter on a permanent include that permanent entering the battlefield. For example, a creature that normally enters the battlefield with one or more +1/+1 counters will enter with twice that many +1/+1 counters on it. A planeswalker will enter the battlefield with twice its starting loyalty counters.
6/1/2012 Adding loyalty counters to a planeswalker in order to activate a loyalty ability isn’t an effect, so those counters are not doubled.
6/1/2012 Any -1/-1 counters that are placed on a creature because of wither or infect are also not doubled.
6/1/2012 The chaos ability is cumulative. For example, if you roll twice in a turn, tapping a land for mana will cause two mana abilities to trigger.