Carth the Lion
Legendary Creature — Human Warrior
Whenever Carth enters or a planeswalker you control dies, look at the top seven cards of your library. You may reveal a planeswalker card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.
Planeswalkers' loyalty abilities you activate cost an additional [+1] to activate.
Donato Giancola
Modern Horizons 2 (MH2)
• #189Rulings
The total cost of a planeswalker's loyalty ability is calculated before any counters are added or removed. If a loyalty ability normally costs [-3] to activate, you do not remove three counters from it and then put one counter on it. You remove two counters at one time when you pay the cost.
(wotc • 2021-06-18)
If you somehow manage to control two Carths (perhaps because of Spark Double), the cost-changing effect is cumulative. In total, loyalty abilities will cost an additional [+2] to activate.
(wotc • 2021-06-18)
If an effect replaces the number of counters that would be placed on a planeswalker, such as that of Vorinclex, Monstrous Raider, that replacement happens only once, at the time payment is made.
(wotc • 2021-06-18)
If a planeswalker's loyalty ability normally has a cost of [+1], Carth's ability makes it cost [+2] instead. A cost of [0] would become [+1], and a cost of [-6] would become [-5].
(wotc • 2021-06-18)
Rulings
The total cost of a planeswalker's loyalty ability is calculated before any counters are added or removed. If a loyalty ability normally costs [-3] to activate, you do not remove three counters from it and then put one counter on it. You remove two counters at one time when you pay the cost.
(wotc • 2021-06-18)
If you somehow manage to control two Carths (perhaps because of Spark Double), the cost-changing effect is cumulative. In total, loyalty abilities will cost an additional [+2] to activate.
(wotc • 2021-06-18)
If an effect replaces the number of counters that would be placed on a planeswalker, such as that of Vorinclex, Monstrous Raider, that replacement happens only once, at the time payment is made.
(wotc • 2021-06-18)
If a planeswalker's loyalty ability normally has a cost of [+1], Carth's ability makes it cost [+2] instead. A cost of [0] would become [+1], and a cost of [-6] would become [-5].
(wotc • 2021-06-18)