Clan Guildmage’s second ability doesn’t untap the land that becomes a creature.
, : Target creature can't block this turn.
, : Target land you control becomes a 4/4 Elemental creature with haste until end of turn. It's still a land.
Activating Clan Guildmage’s first ability after a creature has blocked won’t remove the blocking creature from combat or cause the creature it blocked to become unblocked.
: Target creature can't block this turn.