Doubling Season

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.
If an effect would put one or more counters on a permanent you control, it puts twice that many of those counters on that permanent instead.

Jund

Whenever a player casts a creature spell that's black, red, or green, it gains devour 5. (As the creature enters, its controller may sacrifice any number of creatures of their choice. The creature enters with five times that many +1/+1 counters on it.)
Whenever chaos ensues, create two 1/1 red Goblin creature tokens.

Parallel Lives

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.

Primal Vigor

If one or more tokens would be created, twice that many of those tokens are created instead.
If one or more +1/+1 counters would be put on a creature, twice that many +1/+1 counters are put on that creature instead.

Second Harvest

For each token you control, create a token that's a copy of that permanent.

Prossh, Skyraider of Kher

When you cast this spell, create X 0/1 red Kobold creature tokens named Kobolds of Kher Keep, where X is the amount of mana spent to cast it.
Flying
Sacrifice another creature: Prossh, Skyraider of Kher gets +1/+0 until end of turn.