Rin and Seri, Inseparable
Legendary Creature — Dog Cat
Whenever you cast a Dog spell, create a 1/1 green Cat creature token.
Whenever you cast a Cat spell, create a 1/1 white Dog creature token.
, 
: Rin and Seri deals damage to any target equal to the number of Dogs you control. You gain life equal to the number of Cats you control.
Rin and Seri, Inseparable
Legendary Creature — Dog Cat
Whenever you cast a Dog spell, create a 1/1 green Cat creature token.
Whenever you cast a Cat spell, create a 1/1 white Dog creature token.
, : Rin and Seri deals damage to any target equal to the number of Dogs you control. You gain life equal to the number of Cats you control.
Andrea Radeck
Secret Lair Drop (SLD)
• #1554Rulings
If the chosen target is an illegal target by the time Rin and Seri's last ability tries to resolve, the ability won't resolve. You won't gain life.
(wotc • 2020-06-23)
Rin and Seri's first two abilities don't trigger when you cast Rin and Seri.
(wotc • 2020-06-23)
An ability that triggers when a player casts a spell resolves before the spell that caused it to trigger. It resolves even if that spell is countered.
(wotc • 2020-06-23)
The amount of damage Rin and Seri's last ability deals is determined only as that ability resolves. If Rin and Seri is still on the battlefield, it'll count itself.
(wotc • 2020-06-23)
Rulings
If the chosen target is an illegal target by the time Rin and Seri's last ability tries to resolve, the ability won't resolve. You won't gain life.
(wotc • 2020-06-23)
Rin and Seri's first two abilities don't trigger when you cast Rin and Seri.
(wotc • 2020-06-23)
An ability that triggers when a player casts a spell resolves before the spell that caused it to trigger. It resolves even if that spell is countered.
(wotc • 2020-06-23)
The amount of damage Rin and Seri's last ability deals is determined only as that ability resolves. If Rin and Seri is still on the battlefield, it'll count itself.
(wotc • 2020-06-23)