Any other effects of that damage, such as life gain from lifelink, still apply.
Jawbone Duelist
Conversely, replacement effects that apply to the number of counters put on a player can modify the counters placed this way. For example, Vorinclex, Monstrous Raider's last two abilities can apply to counters placed this way.
Multiple instances of toxic are cumulative. For example, if a creature has toxic 2 and gains toxic 1 due to another effect, combat damage that creature deals to a player will cause that player to get 3 poison counters.
Magic: The Gathering · ™ & © Wizards of the Coast · Illus. Nino Vecia
Card data via Scryfall. Rarix is fan-made; not endorsed by the rights holders.
