Myrkul, Lord of Bones

As long as your life total is less than or equal to half your starting life total, Myrkul, Lord of Bones has indestructible.
Whenever another nontoken creature you control dies, you may exile it. If you do, create a token that's a copy of that card, except it's an enchantment and loses all other card types.

Calix, Guided by Fate

Constellation — Whenever Calix, Guided by Fate or another enchantment you control enters, put a +1/+1 counter on target creature.
Whenever Calix or an enchanted creature you control deals combat damage to a player, you may create a token that's a copy of a nonlegendary enchantment you control. Do this only once each turn.

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.

Archon of Sun's Grace

Flying, lifelink
Pegasus creatures you control have lifelink.
Constellation — Whenever an enchantment you control enters, create a 2/2 white Pegasus creature token with flying.