Enchanted creature gets +4/+4 and has first strike, and all creatures able to block it do so.
Totem armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)
6/1/2012 Indrik Umbra does not give any creature the ability to block the enchanted creature. It just forces those creatures which are already able to block that creature to do so.
6/1/2012 If, during a player’s declare blockers step, a creature is tapped or it’s affected by a spell or ability that says it can’t block, then it doesn’t block. If there’s a cost associated with having a creature block, its controller isn’t forced to pay that cost. The creature doesn’t have to block.