As this land enters, you may pay 2 life. If you don't, it enters tapped.
Temple Garden is premium fixing for any Selesnya (GW) deck, and one of the best dual lands you can run. The key is its typing: it's a Forest and a Plains, which means it fetches with both basic-land tutors (Farseek, Three Visits, Nature's Lore, Wood Elves) and untaps for Cloudpost-style synergies. That flexibility makes it strictly better than a basic and far more reliable than a tapland.
The pay-2-life-or-tapped clause is the entire pitch: in a 40-life format, paying 2 life to come in untapped is almost always correct. Commander games are slow enough that the life rarely matters, while a tapped land on a key turn can cost you a swing.
Run it in essentially every two-or-more-color deck with GW in its identity — tokens, +1/+1 counters, lifegain, Selesnya midrange, all want it.
The only reason not to: ultra-budget builds (it's pricey) or mono-color decks that don't need the fixing.
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