Does a creature with shroud prevent its controller from targeting it with their own spells?

Shroud is a static ability that reads: 'This permanent can't be the target of spells or abilities.' Critically, this restriction applies to all players, not just opponents. CR 702.18a defines shroud this way, making no distinction between friendly and hostile targeting.

This means if you control a creature with shroud, you cannot target it with your own pump spells, auras, equipment-attach abilities, or any other spell or ability that requires a target. The creature is simply untargetable by anyone.

This is one of the key differences between shroud and hexproof. Hexproof (CR 702.11a) only prevents opponents from targeting the creature, so its controller can still target it freely. Shroud offers broader protection but at the cost of your own access.

Concrete example: You control a Morphling (which has shroud) and you cast Giant Growth targeting it. Giant Growth is illegal — Morphling cannot be targeted, even by you — so you must choose a different legal target or the spell cannot be cast that way.

If you want a creature you can protect but still target yourself, look for hexproof instead of shroud. (CR 702.18a, 702.11a)