Скачать или смотреть [F2P] Lazy Sunday in Fire Emblem Heroes? Farm Xander for Hero Merit!

[Note: Sunday is the most practical choice for a general audience in this context, and this method requires less setup than other videos I've seen, other than Summoner Support.]

This is an extremely easy way to farm Hero Merit from the Lunatic battle against Xander every Sunday, as long as you have your free Legendary Ike and are willing to Summoner Support him for this task. You can research other F2P farming methods to build up his support quickly.

Equip Radiant Aether and Warding Breath, give him Quick Riposte 1 (or equip the seal), put him in the first or third slot, unequip your other three characters, and auto-battle.

You can shorten the fight by a turn with either:
Seal Atk/Def 2 in the B slot with Quick Riposte seal, or
Atk Smoke 3 in the C slot or as a seal

Note that this is also doable with only A-rank support, but requires equipping Quick Riposte as a seal and Seal Atk/Def 2 in the B slot.