If you had a card with ":symtap:: Add to your mana pool if you control no untapped permanents", am I correct in believing that only one copy of this card can be useful at a time (that is, you can't activate both and have them both make mana without doing something janky). If so, are there any suggestions on how this could be worded so that this is not the case?
Eresthein Observatory
Land - Observatory
:symtap:: Add
Obviously, one colorless mana for this guy is a little weak.
Instant
Target spell or permanent's tone becomes playful.