Land on gas giant

	‘There is an umbilicus, a root that goes down from the very centre of this habitat complex,’ said Jurisian. ‘I have re-examined the augur soundings of the fleet, my lord. There is a hint of something else down there, a little above the metallic boundary. Perhaps another habitat.’
‘Then we go down,’ said Helbrecht.
‘My lord, the pressure of the planet’s air increases a thousandfold. It is too great,’ said Ceonulf. ‘And the heat...’
‘Terminator armour is proof against such pressures and such heat,’ said Helbrecht. ‘Send for mine.’
The castellan was not to be dissuaded. ‘My Lord Helbrecht, to go down there is tantamount to suicide. Let others go in your stead.’
‘Do not say to me that I am of greater worth than other servants of the Emperor!’ said Helbrecht in a sudden rage. ‘This is my inaugural crusade. I called it. It falls to me to finish it. If I am to expire, so be it. I do so gladly in the service of the Lord of Man.’
None dared gainsay him.
...
	There, on the very boundary of a place where the conditions were inimical to all life, the fiends had their last outpost in the galaxy of man.
The stalk was half a kilometre wide, made of huge cords thicker than an armoured battle-brother and stronger than plasteel. Even so, by rights it should have been shredded, and it was not. The cord and the pregnant structure that fruited from it were still, untroubled by the liquid winds that spent their fury upon them.
...
	Helbrecht, Gulvein and four others materialised – Sword Brothers Aelfgar, Sotrnem, Giraldus and Leofric. They skidded sideways in the wind. Safety lines deployed automatically from their armour, anchoring them to the alien structure. Aelfgar reached for Sotrnem, steadying him before he could be blown away.
Helbrecht looked at his Sword Brothers, their outlines wavering in the boiling hydrogen fluid. His armour creaked under the immense pressure. Currents yanked at him, threatening to push him from the structure to his death even in his Terminator armour. His movements were slow, his strength waging its own war against an entire planet. Status screed redlined all over his visor display, numbers jittering only increments below the armour’s utmost tolerances. He dismissed them in irritation.
...
	Helbrecht fell through air no thicker than that of the Eternal Crusader. He landed hard on a pile of bones that shattered under his weight. Dragged down by his armour, he plunged deep into them, their broken ends closing over his head.
...
	Helbrecht and the thing duelled, neither forcing an advantage. They pushed each other back and forth across the chamber, Helbrecht’s boots stamping the bone upon the floor to powder. The creature was quicker than he, but Helbrecht was stronger and far more heavily armoured. The creature’s only defence was its speed. Neither showed any sign of tiring. The daemonkin was possessed of unnatural vitality, while Helbrecht was bestowed with the gifts of the Emperor. He sang hymns of hate as they fought, yelling into the face of the creature’s silence.
And so the duel could have progressed, the two locked in mortal combat until one stumbled, perhaps days later. But it was not to be.
...
	The creature made a desperate lunge, a movement too quick for an unenhanced man to see, but Helbrecht deflected it.
‘Hurry, Gulvein!’ Helbrecht recognised Sotrnem’s voice. ‘The light is going out!’
‘He sees us! Praise be, he sees us!’ said Gulvein. ‘He lives!’
From the shadows of the alien’s lair an outstretched hand emerged, dripping alien gore and steaming with boiling hydrogen vapour. Gulvein was peering through a crack in space at Helbrecht, distorted horribly. To Helbrecht, Gulvein’s hand was normally sized, but his head appeared monstrous, as if viewed through a flawed lens.

Uncanny Crusade