Impostor Syndrome

Whenever a nontoken creature you control deals combat damage to a player, create a token that's a copy of it, except it isn't legendary.

Arasta of the Endless Web

Reach
Whenever an opponent casts an instant or sorcery spell, create a 1/2 green Spider creature token with reach.

Getting

Emet-Selch of the Third Seat

Spells you cast from your graveyard cost {2} less to cast.
Whenever one or more opponents lose life, you may cast target instant or sorcery card from your graveyard. If that spell would be put into your graveyard, exile it instead. Do this only once each turn.

Friendly Neighborhood

Enchant land
When this Aura enters, create three 1/1 green and white Human Citizen creature tokens.
Enchanted land has "{1}, {T}: Target creature gets +1/+1 until end of turn for each creature you control. Activate only as a sorcery."

Lyla, Holographic Assistant

Whenever you draw a card, put a +1/+1 counter on target creature.

Iron Spider, Stark Upgrade

Vigilance
{T}: Put a +1/+1 counter on each artifact creature and/or Vehicle you control.
{2}, Remove two +1/+1 counters from among artifacts you control: Draw a card.

Benthic Biomancer

{1}{U}: Adapt 1. (If this creature has no +1/+1 counters on it, put a +1/+1 counter on it.)
Whenever one or more +1/+1 counters are put on this creature, draw a card, then discard a card.