18 Apr 2017
If a creature with wither or infect deals damage to a creature, the controller of the creature with wither or infect puts that many -1/-1 counters on the second creature.
14 Jul 2017
If Obelisk Spider deals combat damage to a creature at the same time Obelisk Spider is dealt lethal damage, its first triggered ability will put a -1/-1 counter on the other creature. However, because Obelisk Spider has left the battlefield before that ability resolves, its last ability won’t trigger.
14 Jul 2017
Obelisk Spider’s first triggered ability puts only one -1/-1 counter on the creature, no matter how much combat damage it dealt.
14 Jul 2017
Because damage remains marked on a creature until it’s removed as the turn ends, the counter Obelisk Spider’s first triggered ability puts on a creature may cause previously marked damage to become lethal.
14 Jul 2017
If Obelisk Spider deals combat damage to a creature but that creature isn’t on the battlefield as Obelisk Spider’s first triggered ability resolves, most likely because Obelisk Spider killed that creature already, that ability won’t put a -1/-1 counter on it.
14 Jul 2017
In a Two-Headed Giant game, Obelisk Spider’s last ability causes the opposing team to lose 2 life and you gain 1 life.
14 Jul 2017
If you put one or more -1/-1 counter on each of multiple creatures at the same time, Obelisk Spider’s last ability triggers once for each of those creatures.