Mogis's Warhound

The controller of Mogis's Warhound or the creature it's enchanting chooses which player or planeswalker to attack.

If, during your declare attackers step, Mogis's Warhound (or the creature it enchants) is tapped, is affected by a spell or ability that says it can't attack, or hasn't been under its controller's control continuously since the turn began (and doesn't have haste), then it doesn't attack. If there's a cost associated with having a creature attack, its controller isn't forced to pay that cost, so it doesn't have to attack in that case either.

You still control the Aura, even if it's enchanting a creature controlled by another player.

Unlike other Auras, an Aura with bestow isn't put into its owner's graveyard if it becomes unattached. Rather, the effect making it an Aura ends, it loses enchant creature, and it remains on the battlefield as an enchantment creature. It can attack (and its {T} abilities can be activated, if it has any) on the turn it becomes unattached if it's been under your control continuously, even as an Aura, since your most recent turn began.

On the stack, a spell with bestow is either a creature spell or an Aura spell. It's never both, although it's an enchantment spell in either case.

Unlike other Aura spells, an Aura spell with bestow isn't countered if its target is illegal as it begins to resolve. Rather, the effect making it an Aura spell ends, it loses enchant creature, it returns to being an enchantment creature spell, and it resolves and enters the battlefield as an enchantment creature.