Doombot Harbinger

At the beginning of combat on your turn, if you've cast a noncreature spell this turn, create a 0/3 colorless Wall creature token with defender and reach. Whenever you attack, you may pay RGWU. When you do, target creature gets +1/+0 until end of turn for each creature you control and can't be blocked this turn.

Vigilance, reach At the beginning of combat on your turn, if you've cast a noncreature spell this turn, draw a card. RGWU, T: Copy target triggered ability you control twice. You may choose new targets for the copies.

At the beginning of combat on your turn, if you've cast a noncreature spell this turn, Human Torch gains flying, double strike, and haste until end of turn. Whenever Human Torch attacks, you may pay RGWU. If you do, until end of turn, whenever he deals combat damage to an opponent, he deals that much damage to each other opponent.

Trample At the beginning of combat on your turn, if you've cast a noncreature spell this turn, put four +1/+1 counters on The Thing. Whenever The Thing attacks, you may pay RGWU. When you do, double the number of each kind of counter on any number of target permanents you control.

Whenever another Hero you control enters, it gains vigilance and haste until end of turn. Put a +1/+1 counter on that Hero and a +1/+1 counter on Captain America.

Whenever you discard one or more land cards, each opponent loses 2 life. At the beginning of combat on your turn, target Villain you control gains menace until end of turn. It connives. (Draw a card, then discard a card. If you discarded a nonland card, put a +1/+1 counter on that creature.)

Whenever T'Challa enters or attacks, create a tapped Vibranium token. (It's an artifact with indestructible and "T: Add C. This mana can't be spent to cast a nonartifact spell.") Whenever you cast an artifact spell with mana value 4 or greater, put two +1/+1 counters on T'Challa.

Flying, trample, indestructible When Galactus enters, exile target permanent. Insatiable Hunger — Galactus attacks an opponent with the most life among your opponents each combat if able unless you control a creature named Silver Surfer, Galactus's Herald.