Leyline of Abundance
Enchantment
If Leyline of Abundance is in your opening hand, you may begin the game with it on the battlefield.
Whenever you tap a creature for mana, add an additional .
: Put a +1/+1 counter on each creature you control.
Illustrated by
Core Set 2020 Promos#179sRareEnglishLegality
Rulings
Jul 12, 2019
An ability that triggers “whenever you tap a creature for mana” triggers only if you activate a mana ability of a creature including 
in its cost. Mana abilities that don’t include the symbol and instead say “Tap an untapped creature you control” or similar won’t cause Leyline of Abundance’s second ability to trigger. Similarly, it won’t trigger if you tap a creature to activate a mana ability of another object (even if that mana ability also includes ).