You have a way to put a +1/+1 counter on a creature you control.
Steps
Put a +1/+1 counter on a creature you control.
Moss-Pit Skeleton triggers, putting itself on top of your library.
Desecrated Tomb and Insidious Roots trigger.
Resolve the Desecrated Tomb trigger, creating a 1/1 Bat creature token.
When the Bat enters the battlefield, Snarling Gorehound triggers, causing you to surveil 1, putting Moss-Pit Skeleton into your graveyard from the top of your library.
Resolve the Insidious Roots trigger, creating a 0/1 Plant creature token, then putting a +1/+1 counter on each Plant you control.
Moss-Pit Skeleton and Snarling Gorehound trigger.
Resolve the Snarling Gorehound trigger, causing you to surveil 1.
Resolve the Moss-Pit Skeleton trigger, putting it on top of your library.