Ichor Rats

• WWizards of the Coast2011-01-01
  Official Ruling
  A player who has ten or more poison counters loses the game. This is a state-based action.
• WWizards of the Coast2011-01-01
  Official Ruling
  If Ichor Rats's last ability causes each player to have ten poison counters, the game is a draw.
• WWizards of the Coast2011-01-01
  Official Ruling
  Damage from a source with infect is damage in all respects. If the source with infect also has lifelink, damage dealt by that source also causes its controller to gain that much life. Damage from a source with infect can be prevented or redirected. Abilities that trigger on damage being dealt will trigger if a source with infect deals damage, if appropriate.
• WWizards of the Coast2011-01-01
  Official Ruling
  If damage from a source with infect that would be dealt to a player is prevented, that player doesn't get poison counters. If damage from a source with infect that would be dealt to a creature is prevented, that creature doesn't get -1/-1 counters.
• WWizards of the Coast2011-01-01
  Official Ruling
  Damage from a source with infect affects planeswalkers normally.
• WWizards of the Coast2011-01-01
  Official Ruling
  Infect's effect applies to any damage, not just combat damage.
• WWizards of the Coast2011-01-01
  Official Ruling
  The -1/-1 counters remain on the creature indefinitely. They're not removed if the creature regenerates or the turn ends.

Rulings via Scryfall