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.

Gruul Signet

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Sol Ring

Jetmir, Nexus of Revels

Creatures you control get +1/+0 and have vigilance as long as you control three or more creatures.
Creatures you control also get +1/+0 and have trample as long as you control six or more creatures.
Creatures you control also get +1/+0 and have double strike as long as you control nine or more creatures.

Selesnya Signet

Anointed Procession

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

Boros Signet

Nature's Lore

Search your library for a Forest card, put that card onto the battlefield, then shuffle.